Vietnamese Purple Yam Soup (Canh Khoai Mỡ)
Canh khoai mỡ is a comforting Southern Vietnamese soup made from purple yam (also called ube). When cooked, the yam releases its starch into the broth, giving it a beautiful purple color and a silky, velvety texture.
After quite a few years living in Saigon, we have grown fond of this simple yet filling soup. The soup is great for daily meals as it is very quick and easy to make. Additionally, we also turn to it when someone in the family is not feeling well, having a stomach upset or toothache.
The soup has a delicate, naturally sweet flavor with a hint of earthiness from the yam. To add more depth, we often cook it with ground pork and chopped shrimp. Some cooks also like to use stock such as pork broth or shrimp stock instead of plain water, which results in a stronger flavor base.
Common garnishes for the soup are chopped scallion, cilantro and saw-tooth leaves. In some restaurants in Saigon, you may even find crispy fried garlic sprinkled on top, adding a subtle crunch and aroma.
Two Preparation Methods for the Yam
The texture of this soup can vary depending on personal preference. Some families enjoy it completely smooth, while others like ourselves prefer to keep some chunks of yam intact in the soup.
What I’m suggesting in this recipe is to divide the yam and prepare in two different ways. We finely grate a portion of the yam which will easily release starch for a creamy texture. The remaining yam is cut into medium-sized chunks, so that after simmering, the pieces turn soft but don’t completely disintegrate. These tender bites add contrast and prevent the soup from becoming too much like a puree.
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Canh Khoai Mỡ (Vietnamese Purple Yam Soup)
Ingredients
- 24 oz purple yam
- cooking oil
- 1 tablespoon finely minced shallots
- 5 oz ground pork
- 1½ teaspoons salt
- 5 cups water (or stock such as pork broth, shrimp stock)
- 1 teaspoon fish sauce
- 2 oz peeled and deveined shrimp, chopped into small pieces
- fresh herbs for garnish: chopped cilantro, scallion and saw-tooth leaves
Instructions
- Peel the yam. Grate about half to create starch for a smooth broth, and roughly chop the rest into medium sized chunks for texture.
- In a pot, heat some cooking oil over medium heat and sauté the minced shallots until fragrant (about 2–3 minutes).
- Add the ground pork and sauté briefly then add the salt. Continue to stir and cook until no longer pink on the outside.
- Add the water to the pot and bring it to a boil. Then add all of the yam. Let the liquid come back to a simmer and skim off all the foam.
- Continue to simmer over medium heat until the yam is tender to your liking and the soup turns purple, about 15 minutes. Give the soup a stir every now and then to prevent sticking. Add fish sauce and adjust seasonings to taste.
- Stir in the chopped shrimp. Once the shrimp is cooked through (which is very quick), turn off the heat and transfer the soup to serving bowls.
- Sprinkle fresh herbs and serve hot.
Notes
- Some home cooks in Vietnam like to add a touch of sugar to round out the flavors and enhance the sweetness of the yam.
- In some restaurants, you may find the soup topped with crispy fried garlic bits, which bring extra aroma and a subtle crunch.
