Purple Yam Soup: How to Make Vietnamese Canh Khoai Mo at Home | Authentic Recipe

Looking for a comforting Vietnamese soup that warms the soul? Canh khoai mo (purple yam soup) is a traditional dish that combines the stunning violet hue of purple yams with a delicate, savory broth that’s both nourishing and visually striking.

This simple yet elegant soup holds a special place in Vietnamese home cooking. The earthy sweetness of purple yams balances perfectly with the umami-rich broth, creating a harmonious flavor profile that’s been cherished for generations. Whether you’re fighting off a cold or simply craving something wholesome, this soup delivers both comfort and nutrition in every spoonful.

You’ll love how the vibrant purple color transforms an ordinary meal into something extraordinary. And don’t worry about complex techniques—this recipe keeps things straightforward while honoring authentic Vietnamese flavors.

What Is Canh Khoai Mo (Vietnamese Purple Yam Soup)?

Canh khoai mo is a traditional Vietnamese soup featuring purple yams simmered in a savory broth that balances earthy sweetness with rich umami flavors. This homestyle dish showcases the striking violet hue of purple yams (khoai mỡ) which maintain their vibrant color even after cooking. The soup typically combines tender chunks of purple yam with protein such as pork ribs or ground pork plus aromatics like lemongrass green onions and fish sauce.

Vietnamese families prepare this nourishing soup throughout the year but it becomes especially popular during cooler months when its warming qualities are most appreciated. The natural sweetness of the purple yams contrasts beautifully with the savory elements creating a comforting balance that exemplifies Vietnamese cuisine’s harmony of flavors.

Unlike other Vietnamese soups that might require complex broths or many herbs canh khoai mo remains relatively straightforward to prepare. The simplicity allows the unique properties of the purple yam to shine through while still delivering the depth of flavor characteristic of Vietnamese cooking. Many regional variations exist throughout Vietnam with some versions incorporating additional vegetables or different protein options depending on local preferences and ingredient availability.

This soup represents more than just sustenance in Vietnamese culture; it embodies the comfort food tradition where simple ingredients transform into something greater through thoughtful preparation. The resulting dish delivers not only nutritional benefits but also the distinctive satisfaction that comes from authentic homestyle cooking.

Why You’ll Love This Traditional Vietnamese Soup

This purple yam soup (canh khoai mo) will quickly become a favorite in your recipe collection for many compelling reasons. The vibrant purple color immediately catches your eye when served, making it an impressive dish for family meals or gatherings.

Your taste buds will appreciate the perfect balance between the natural sweetness of purple yams and the savory depth of the broth. Each spoonful delivers a harmonious blend of earthy sweetness and umami richness that defines authentic Vietnamese home cooking.

The nourishing qualities of this soup make it especially appealing during cooler months when you crave something both warming and satisfying. Purple yams provide substantial nutrition while the clear broth makes the dish feel light and digestible.

You can easily adapt this recipe to suit your dietary preferences by switching between pork ribs, ground pork, or even vegetarian options. The versatility extends to the aromatics as well, allowing you to adjust lemongrass, green onions, and other seasonings to your taste.

Meal prep enthusiasts will appreciate how the flavors deepen overnight, making this soup even more delicious as leftovers. The straightforward preparation process requires minimal active cooking time, letting you focus on other dishes while the soup simmers to perfection.

Those new to Vietnamese cooking will find this recipe approachable yet authentic. Unlike more complex Vietnamese soups that require many specialized ingredients, canh khoai mo showcases how Vietnamese cuisine can transform simple components into extraordinary dishes through thoughtful preparation.

Your kitchen will fill with enticing aromas as the purple yams release their natural sweetness into the broth, creating an inviting atmosphere that draws everyone to the table before the meal even begins.

Key Ingredients For Canh Khoai Mo

Creating authentic canh khoai mo requires several key ingredients that contribute to its distinctive flavor profile and beautiful purple hue. Each component plays an essential role in developing the signature taste of this beloved Vietnamese soup.

Purple Yam (Khoai Mo)

Purple yam serves as the star ingredient in this traditional Vietnamese soup, providing both its name and characteristic color. Look for firm purple yams with smooth skin and vibrant purple flesh when shopping at Asian markets or specialty grocers. You should peel and cut the yams into uniform 1-inch chunks to ensure even cooking throughout the soup. The natural sweetness of purple yams balances perfectly with the savory elements of the broth, creating a harmonious flavor profile that defines this dish. Purple yams also release a natural starch during cooking that helps thicken the soup slightly, giving it a satisfying consistency without requiring additional thickeners.

Pork Ribs

Pork ribs contribute essential richness and depth to canh khoai mo, infusing the broth with savory flavor as they simmer. Select meaty pork ribs and cut them into 2-inch pieces for optimal flavor extraction during cooking. You should blanch the ribs briefly in boiling water before adding them to the soup to remove impurities and ensure a clean-tasting broth. The collagen in pork ribs gradually breaks down during cooking, adding body to the soup while the meat becomes tender enough to fall off the bone. For a leaner alternative, ground pork can substitute for ribs, though the resulting broth will have a slightly different texture and richness.

Vietnamese Herbs And Seasonings

Vietnamese seasonings transform this simple soup into a fragrant and flavorful dish that exemplifies the country’s culinary traditions. Fish sauce provides essential umami depth and should be added gradually to taste rather than all at once. Fresh lemongrass, bruised and cut into 3-inch sections, infuses the broth with citrusy aromatics that complement the earthiness of the purple yams. Green onions contribute both flavor during cooking and freshness when sprinkled on top before serving. You should include a few slices of fresh ginger to add warmth and subtle spice that balances the sweetness of the yams. Optional ingredients like Vietnamese coriander (rau răm) or cilantro can be added just before serving to introduce bright herbal notes to the finished soup.

Equipment Needed

Preparing canh khoai mo requires minimal equipment that most home kitchens already have. These basic tools will help you create this comforting Vietnamese purple yam soup with ease:

• Large pot or Dutch oven (4-6 quart capacity)
• Sharp chef’s knife for cutting purple yams
• Cutting board
• Vegetable peeler
• Measuring spoons and cups
• Wooden spoon or heat-resistant spatula
• Ladle for serving
• Soup bowls
• Fine mesh strainer (optional for skimming broth)
• Small bowl for mixing seasonings

Your large pot serves as the primary cooking vessel where the broth develops its rich flavors while the yams soften to perfection. A sharp knife makes quick work of cutting the dense purple yams into evenly sized chunks that cook uniformly. The vegetable peeler removes the tough outer skin from the yams without wasting the precious flesh beneath.

Standard measuring tools ensure your seasonings maintain the proper balance between savory and sweet elements essential to authentic canh khoai mo. The wooden spoon allows gentle stirring without damaging the tender yam pieces once they’ve softened. A proper ladle transfers both broth and chunky ingredients to serving bowls while maintaining the beautiful presentation.

Many Vietnamese home cooks use a fine mesh strainer to achieve a clearer broth by removing any impurities that rise to the surface during simmering. This step enhances both the visual appeal and clean flavor profile of your finished soup.

How To Prepare Purple Yam

Properly preparing purple yam is essential for achieving the perfect texture and flavor in your canh khoai mo. The distinctive characteristics of this root vegetable require exact handling techniques to maximize its qualities in the soup.

Selecting The Perfect Yam

Look for purple yams that feel firm and heavy for their size without any soft spots. The skin should appear relatively smooth with minimal blemishes or wrinkles which often indicate age. Fresh purple yams typically have a rich dark purple to brownish exterior depending on the variety. Try to choose medium-sized yams that are uniform in shape as they will cook more evenly in your soup. Avoid specimens with sprouts or those that feel excessively light which may indicate dryness. Most Asian markets and specialty grocery stores stock purple yams year-round though they may be labeled as ube or purple sweet potatoes. For canh khoai mo the fresher the yam the more vibrant your soup’s color will be and the sweeter its flavor profile.

Peeling And Cutting Techniques

Start by washing the purple yam thoroughly under cold water to remove any dirt from the skin. Use a sturdy vegetable peeler to remove the thick outer skin with firm downward strokes. You might notice that purple yam stains hands and cutting surfaces so consider wearing food-safe gloves during preparation. After peeling cut the yam in half lengthwise then slice each half into manageable pieces before dicing into 1-inch cubes. Maintain consistent cube sizes to ensure even cooking throughout the soup. Purple yams oxidize quickly once cut so immerse the pieces in cold water if you aren’t using them immediately. When ready to cook drain the water completely and pat the yam pieces dry with paper towels. For best texture in canh khoai mo aim for pieces that will hold their shape during simmering yet become tender enough to absorb the savory broth flavors.

Making The Broth

The soul of canh khoai mo lies in its aromatic broth that perfectly complements the earthiness of purple yams. This foundational element requires careful preparation to achieve the right balance of flavors.

Creating A Flavorful Pork Base

Start by rinsing 1 pound of pork ribs under cold water to remove any bone fragments or impurities. Place the cleaned ribs in a large pot and cover with cold water, then bring to a boil over high heat. After boiling for 2-3 minutes, you’ll notice foam rising to the surface. Drain completely and rinse the ribs again under running water to remove all scum and impurities. This blanching technique ensures a clean, clear broth without any cloudiness.

Return the cleaned ribs to the pot and add 8 cups of fresh water. Add 2 stalks of lemongrass (bruised and cut into 4-inch pieces), 3-4 slices of fresh ginger, and 1 small onion (peeled and halved). Bring this mixture to a boil over high heat then reduce to a gentle simmer. Allow the broth to simmer uncovered for about 45 minutes until the ribs become tender.

Season the broth with 2-3 tablespoons of fish sauce to introduce that essential umami flavor characteristic of Vietnamese soups. Taste and adjust the seasoning as needed, remembering that the sweet purple yams will balance the savory elements of the finished dish. For an extra layer of flavor, add a teaspoon of sugar to enhance the natural sweetness of the ingredients.

Skim any additional foam or fat that rises to the surface during simmering to maintain the broth’s clarity. The resulting liquid should be fragrant with aromatics yet clean tasting, providing the perfect canvas for the purple yams to shine. Your broth is ready when it has a light golden color and pronounced pork aroma with subtle notes of lemongrass and ginger.

Full Recipe For Canh Khoai Mo

Ingredients

For the Broth:

• 1 pound pork ribs, cut into 2-inch pieces
• 8 cups water
• 2 stalks lemongrass, bruised and cut into 4-inch pieces
• 3 slices fresh ginger
• 1 small onion, halved
• 2 tablespoons fish sauce
• 1 teaspoon sugar
• Salt to taste

For the Soup:

• 1.5 pounds purple yam (khoai mo), peeled and cut into 1-inch cubes
• 2 green onions, thinly sliced
• 2 tablespoons chopped cilantro
• 1 tablespoon fried shallots (optional)
• Fresh lime wedges for serving

Instructions

1. Prepare the pork ribs: Rinse the pork ribs under cold water. Place them in a pot and cover with cold water. Bring to a boil and cook for 2 minutes. Drain and rinse the ribs under cold water to remove impurities.
2. Make the broth: In a large pot, add the cleaned pork ribs and 8 cups of water. Bring to a boil over high heat. Reduce heat to medium-low and add lemongrass, ginger, and onion. Simmer for 45 minutes, skimming any foam that rises to the surface.
3. Season the broth: Add fish sauce and sugar to the broth. Taste and adjust seasoning with additional salt if needed.
4. Cook the purple yam: Add the cubed purple yam to the simmering broth. Cook for 15-20 minutes until the yam is tender but still holds its shape. The broth will take on a slight purple tint from the yams.
5. Finish the soup: Remove the lemongrass, ginger, and onion from the broth. Add half of the sliced green onions and stir gently.
6. Serve: Ladle the hot soup into bowls, ensuring each serving contains pieces of pork rib and purple yam. Garnish with remaining green onions, chopped cilantro, and fried shallots if using. Serve with lime wedges on the side.

Cooking Tips

• Keep the broth at a gentle simmer rather than a rolling boil to maintain clarity.
• The purple yam should be firm enough to hold its shape in the soup but tender enough to easily pierce with a fork.
• For a clearer broth, strain it through a fine-mesh sieve before adding the purple yam.
• This soup tastes even better the next day as the flavors continue to develop.

Serving Suggestions

• Serve canh khoai mo as part of a traditional Vietnamese meal alongside steamed rice and other dishes.
• Pair with simple protein dishes like grilled fish or stir-fried vegetables for a balanced meal.
• Add a small side dish of Vietnamese dipping sauce (nuoc cham) to complement the meal.
• For a complete experience, serve with fresh herbs like Thai basil or Vietnamese coriander on the side.

Step-By-Step Cooking Instructions

Follow these detailed instructions to create a perfect bowl of canh khoai mo that balances the earthy sweetness of purple yams with the rich savory broth. This traditional Vietnamese soup comes together through three main stages.

Preparing The Meat

Start by thoroughly rinsing 1 pound of pork ribs under cold water to remove any bone fragments or impurities. Fill a large pot with enough water to cover the ribs completely and bring it to a rolling boil. Add the pork ribs to the boiling water and blanch for 3-5 minutes until the exterior turns opaque. Remove the ribs from the water and rinse them again under cold water to wash away any remaining impurities. This blanching technique ensures your final broth will be clear and clean-tasting.

Place the blanched ribs in a large pot with 8 cups of fresh water along with 2 stalks of lemongrass (bruised and cut into segments), 3 slices of ginger, and half an onion. Bring this mixture to a boil before reducing the heat to maintain a gentle simmer. Allow the broth to cook uncovered for 45-60 minutes until the pork becomes tender. Skim off any foam or fat that rises to the surface throughout the cooking process to maintain the broth’s clarity. Season the broth with 2 tablespoons of fish sauce and 1 teaspoon of sugar, adjusting to taste as needed.

Cooking The Purple Yam

While the broth simmers, prepare your purple yams for cooking. Heat 1 tablespoon of vegetable oil in a separate pan over medium heat. Add 1 tablespoon of minced garlic and sauté until fragrant but not browned, approximately 30 seconds. Add the cubed purple yams (about 1 pound) to the pan and stir-fry for 2-3 minutes until they develop a slight sheen. This quick sauté helps the yams maintain their shape during the simmering process.

Transfer the sautéed yams to the pot with the simmering broth after the meat has been cooking for at least 40 minutes. Gently stir to distribute the yams evenly throughout the broth. Continue simmering for 15-20 minutes until the yams are tender when pierced with a fork but still holding their shape. Avoid overcooking as purple yams can become mushy and disintegrate into the broth.

Combining The Soup

Once both the meat and yams are tender, taste the soup and adjust the seasoning if necessary. Add additional fish sauce for saltiness or a pinch more sugar to balance the flavors. The broth should have a light golden color with a fragrant aroma from the lemongrass and ginger. Remove the lemongrass stalks, ginger slices, and onion pieces before serving.

Ladle the hot soup into individual serving bowls, ensuring each portion contains a generous amount of purple yam pieces and pork. Sprinkle with freshly chopped green onions and cilantro for brightness and added aroma. For an extra layer of flavor, add a crack of fresh black pepper on top just before serving. The vibrant purple color of the yams creates a striking visual contrast against the golden broth, making this dish as beautiful as it is delicious.

Serve canh khoai mo immediately while hot alongside steamed rice and other Vietnamese dishes for a complete meal. The soup can be stored in an airtight container in the refrigerator for up to 3 days, with flavors that continue to develop and improve overnight.

Serving Suggestions

Canh khoai mo shines brightest when paired thoughtfully with complementary dishes that enhance its flavors and create a balanced Vietnamese meal. Serve this vibrant purple yam soup in individual bowls alongside steamed white jasmine rice which provides the perfect neutral base to absorb the flavorful broth. The rice’s subtle aroma works beautifully with the earthy sweetness of the purple yams.

For a traditional Vietnamese family-style meal add grilled or braised meat dishes such as thịt kho (caramelized pork) or cá kho tộ (caramelized fish in clay pot). These savory proteins offer textural contrast to the soft purple yams in your soup. Include a simple stir-fried vegetable dish like water spinach with garlic (rau muống xào tỏi) to bring freshness and crunch to the meal.

Enhance your soup presentation by garnishing each bowl with additional fresh herbs just before serving. Sprinkle thinly sliced green onions cilantro leaves or Thai basil across the top for vibrant color and aromatic fragrance. A small dish of freshly sliced bird’s eye chilies offers guests the option to add heat according to their preference.

Serve canh khoai mo hot especially during cooler weather when its warming qualities are most appreciated. The soup can function as a starter course for more elaborate meals or stand as the main soup component in a simpler dinner setting. Vietnamese meals typically feature several dishes served simultaneously allowing diners to experience a range of complementary flavors and textures.

For a complete nutritional experience consider adding a small dish of pickled vegetables like đồ chua (pickled carrots and daikon) which provides acidity to balance the sweetness of the purple yams. The pickled elements help cleanse the palate between bites of different dishes creating a harmonious dining experience that showcases the balance so valued in Vietnamese cuisine.

Storage And Reheating Tips

Proper storage extends the life of your canh khoai mo while preserving its delicious flavors. Allow the soup to cool completely before transferring it to airtight containers. Refrigerate for up to 3 days for optimal freshness and flavor development. The purple yam may absorb more broth during storage making the soup thicker but the flavors will continue to meld and deepen overnight.

For freezing portions consider storing the broth and yams separately. The broth freezes well for up to 3 months while the texture of purple yams can change slightly when frozen. If freezing the complete soup use freezer-safe containers leaving about an inch of headspace to allow for expansion.

When reheating canh khoai mo gentle methods work best to maintain the integrity of the purple yam pieces. Warm the soup over medium-low heat in a saucepan stirring occasionally until it reaches a gentle simmer. Avoid boiling vigorously as this can cause the yam chunks to break down and turn mushy.

Microwave reheating works well for single portions. Place your desired amount in a microwave-safe bowl cover loosely and heat in 1-minute intervals stirring between each until thoroughly warmed. Add a splash of water or broth if the soup has thickened too much during storage.

The soup might need readjustment of seasonings after reheating. Taste and add small amounts of fish sauce or salt if needed. Garnish with fresh herbs just before serving to brighten the reheated soup with color and flavor.

Nutritional Benefits Of Canh Khoai Mo

Purple yam soup delivers exceptional nutritional value while satisfying your taste buds. This traditional Vietnamese dish combines many health benefits from its star ingredients.

Powerful Purple Yam Nutrition

Purple yams contain impressive nutritional components that support overall wellness. These vibrant root vegetables are packed with complex carbohydrates that provide sustained energy throughout the day. Their rich anthocyanin content—the compound responsible for the striking purple color—offers potent antioxidant properties that help combat free radicals in your body.

One serving of purple yams (about 100g) provides:

Nutrient	Amount
Calories	118 kcal
Carbohydrates	27g
Fiber	4g
Protein	2g
Vitamin C	27% DV
Potassium	816mg
Manganese	25% DV

The high fiber content in purple yams promotes digestive health and helps maintain steady blood sugar levels. These yams also contain important amounts of vitamin B6 vitamin C and potassium which support immune function heart health and proper muscle contraction.

Protein-Rich Pork Benefits

Pork ribs or ground pork in canh khoai mo contribute essential proteins your body needs for tissue repair and immune function. The meat provides complete protein containing all nine essential amino acids your body cannot produce on its own.

Pork also supplies important micronutrients including:

• B vitamins for energy metabolism
• Zinc for immune support
• Iron for oxygen transport
• Selenium for antioxidant protection

These nutrients work together to support various bodily functions while adding satisfying richness to the soup.

Therapeutic Herbs And Aromatics

The aromatic ingredients in canh khoai mo offer more than just flavor—they provide important health benefits:

Lemongrass contains citral compounds with antimicrobial and anti-inflammatory properties. This fragrant herb may help reduce fever symptoms and aid digestion.

Ginger delivers powerful anti-inflammatory effects through its active compounds including gingerol. Regular consumption may help reduce muscle pain and improve digestive health.

Green onions supply a good dose of vitamin K necessary for proper blood clotting along with sulfur compounds that support detoxification processes in your body.

Low-Calorie Complete Meal Option

Even though its rich flavors canh khoai mo remains relatively low in calories while providing excellent nutritional density. A typical serving contains approximately 250-300 calories depending on the exact ingredients and proportions.

The soup combines complex carbohydrates from purple yams quality proteins from pork and various micronutrients from vegetables and herbs—creating a balanced meal that satisfies hunger without excessive caloric intake.

Heart-Healthy Profile

When prepared with minimal added fat canh khoai mo offers heart-healthy benefits. The potassium in purple yams helps regulate blood pressure while the soup’s moderate protein content supports cardiovascular health.

The clear broth base provides hydration without excessive sodium especially when fish sauce is used judiciously. This makes the soup suitable for those monitoring their salt intake while still enjoying robust flavors.

Conclusion

Canh khoai mo captures the essence of Vietnamese home cooking in a bowl. This vibrant purple yam soup balances earthy sweetness with savory depth making it both visually striking and deeply satisfying.

You’ll find this dish particularly comforting during cooler months when its warming qualities shine. The beauty of canh khoai mo lies in its simplicity – with minimal equipment and straightforward techniques you can create an authentic taste of Vietnam in your kitchen.

Whether you’re serving it with jasmine rice and grilled meats or enjoying it on its own the nutritional benefits are substantial. The purple yams provide essential vitamins and fiber while the aromatic broth delivers both flavor and wellness benefits.

Try this beloved Vietnamese soup and discover how humble ingredients transform into something truly extraordinary through thoughtful preparation.

Frequently Asked Questions

What is Canh Khoai Mo?

Canh Khoai Mo is a traditional Vietnamese soup made with purple yams and savory broth. It features tender chunks of purple yam simmered with protein (typically pork ribs or ground pork) and aromatics like lemongrass and green onions. Known for its comforting qualities, earthy sweetness, and umami-rich flavor, this soup has a distinctive vibrant purple color that adds visual appeal to any meal.

How do I select the best purple yams for this soup?

Choose firm, heavy purple yams with smooth skin and minimal blemishes. Medium-sized yams are ideal for even cooking. The yams should feel dense without soft spots. Fresh purple yams will enhance the soup’s vibrant color and natural sweetness, which is essential for authentic Canh Khoai Mo. Avoid yams with wrinkled skin or sprouts, as these indicate age.

Can I make Canh Khoai Mo vegetarian?

Yes, Canh Khoai Mo can be easily adapted for vegetarians. Simply replace the pork broth with vegetable broth and omit the meat. You can add tofu or mushrooms for protein. Use soy sauce or mushroom sauce instead of fish sauce for seasoning. The purple yams will still provide the signature flavor and color, while vegetable-based aromatics will create a flavorful broth.

How long does it take to prepare Canh Khoai Mo?

Canh Khoai Mo takes approximately 60-90 minutes to prepare from start to finish. The majority of this time is spent simmering the broth to develop rich flavors. Active preparation time is about 20-30 minutes, which includes cleaning and cutting the yams, preparing the pork, and assembling the soup. The straightforward cooking process makes it accessible even for those new to Vietnamese cuisine.

What should I serve with Canh Khoai Mo?

Serve Canh Khoai Mo with steamed jasmine rice as the traditional base. Pair it with grilled or braised meats and stir-fried vegetables for a complete meal. Pickled vegetables provide a nice acidic contrast to the soup’s sweetness. Fresh herbs like cilantro and sliced chilies can be offered as optional garnishes. This soup is particularly satisfying during cooler weather.

How do I store and reheat leftovers?

Store cooled Canh Khoai Mo in airtight containers in the refrigerator for up to three days. For longer storage, freeze the broth separately for up to three months. When reheating, use gentle heat (stovetop or microwave at medium power) to preserve the yam’s texture. Stir carefully to avoid breaking the yams. You may need to adjust seasonings after reheating as flavors can intensify.

What are the nutritional benefits of Canh Khoai Mo?

Canh Khoai Mo offers excellent nutritional benefits. Purple yams provide complex carbohydrates, fiber, vitamin C, and potassium. They also contain antioxidants from their purple pigment. The pork contributes protein and essential micronutrients, while aromatics like lemongrass and ginger offer anti-inflammatory properties. Overall, this soup is low-calorie and heart-healthy while still being satisfying and flavorful.

How do I ensure my broth is clear and flavorful?

For a clear, flavorful broth, blanch the pork ribs first by briefly boiling them and discarding the first water. This removes impurities. Then simmer the meat slowly with aromatics like lemongrass, ginger, and onion. Skim off any foam or fat that rises to the surface during cooking. Avoid rapid boiling, as a gentle simmer extracts flavor without clouding the broth.

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