Canh Khoai Mỡ (Vietnamese purple sweet potato soup)

What is Kankoimo?

Canh khoai mỡ is a traditional Vietnamese vegetable soup from central Vietnam, easily recognizable by its natural purple color derived from purple sweet potatoes.

Canh khoai means “potato and yam soup”. Mỡ means “fat” and refers to the oily, slimy texture of raw, grated purple sweet potatoes.

Purple sweet potato, also known as khoai tím or purple water yam (Dioscorea alata), is called ube in Filipino cuisine and is usually used in sweet desserts.

In Vietnamese cuisine, it is most often grated, scraped with a sharp spoon in the traditional manner, or added to flavorful dishes such as vegetable soups.

This purple sweet potato should not be confused with another root vegetable, yampi root (sometimes spelled yampi) or Okinawan purple sweet potato. But who’s to say it can’t be used as a replacement?

In fact, yangpi root is often used as a substitute when making canh khoai mỡ trắng, a white version of this soup.

Adding grated purple yam to the soup will thicken it a bit and reduce most of its original sliminess.

There are many variations of this soup, the main difference being the protein used.

When cooked with shrimp, it becomes khain koi mo nau tom. When cooked with salted dried shrimp, it becomes kankoi monau tom kaw. When cooked with ground pork, it becomes canh khoai mo nau thit bam.

This recipe uses shrimp. Shrimp naturally adds a subtle sweetness to the soup and is the most traditional.

what you need

To make Vietnamese Khanh Khoi Mo, gather the following ingredients.

Purple sweet potatoes: I just can’t find fresh purple potatoes. Instead, I buy frozen items, which are available at many Asian grocery stores. Look for packages that say frozen grated purple sweet potatoes. Buy something made in Vietnam. It usually only contains grated yam. Frozen yam from the Philippines carries the same label, and because it is made for Ube’s desserts, ingredients are often added to give it a bright purple color. Shrimp: Fresh shrimp of any size. We use frozen shrimp that has been peeled and deveined. Water: For soup stock. Seasonings: Chicken bouillon powder or mushroom seasoning powder (Vietnamese secret umami seasoning), fish sauce, salt, cracked black pepper. Oil: Any cooking oil can be used. You can also use rendered animal fats such as lard or taro for extra flavor. Nose: The usual culprits, fresh garlic and shallots. Fresh garnishes: chopped paddy herbs, spring onions, coriander. I’m currently not into herbs, so I’m only using coriander here.

How to make Kankoimoi

Step 1: Toast Air Freshener

Heat oil in a saucepan over medium heat. Add garlic and shallots. Fry in the pan until lightly toasted (about 30 seconds).

Step 2: Add shrimp

Add the chopped shrimp and fry until pink. Add water and reduce the heat to the pot.

Step 3: Add purple sweet potatoes

Add the grated purple sweet potato and simmer for about 15 minutes until the flavors meld. Stir occasionally and scrape the bottom of the pot, as the yam may settle and burn.

Step 4: Season, plate, and garnish

Add seasonings little by little to taste.

Transfer the soup to a bowl and garnish with a handful of roughly chopped paddy herbs, coriander, green onions, or a combination of all three.

Finish by sprinkling with fresh black pepper to add flavor and enjoy.