Vegetation Profile: Khoai Mỡ

Dioscorea alata, called water yam, winged yam, and purple yam, was first cultivated somewhere in Southeast Asia. Although it is not grown in the same quantities as the African yams it has the largest distribution world-wide of any cultivated yam, being grown in Asia, the Pacific islands, Africa, and the West Indies (Mignouna 2003). In the United States it has become an invasive species in some Southern states.

In the Philippines it is known as ube (or ubi) and is used as an ingredient in many sweet desserts. In India, it is known as ratalu or violet yam or the Moraga Surprise. In Hawaii it is known as uhi. Uhi was brought to Hawaii by the early Polynesian settlers and became a major crop in the 1800s when the tubers were sold to visiting ships as an easily stored food supply for their voyages (White 2003).

Known as khoai mỡ in Vietnam, this yam is used in both sweet and savory dishes. My encounters with khoai mỡ have been pretty limited thus far. I once ordered a cup of che thap cam at Che 278 in District 4 that featured a layer of sweetened khoai mỡ puree. However, now that I know what this purple vegetable is, I’ll be on the lookout for it on menus around town.

According to my mom, the most common preparation of khoai mỡ is in a shrimpy soup called canh khoai mỡ. Coincidentally, The Astronomer recently noticed the owners of one of his favorite bun cha joints slurping down a strange purple broth for their dinner. When he asked what it was, they ladled out an extra bowl for him and invited him to sit down. The soup turned out to be canh khoai mỡ, which he described as “plain.” My mom, on the other hand, couldn’t stop raving about the soup’s deliciousness when I spoke to her. So, I can’t wait to try the yam soup for myself!

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5 Responses to “Vegetation Profile: Khoai Mỡ”


  • My mom makes this soup from time to time and I love it. Not only is it easy to swallow/digest, it has a distinctive and fragrant flavor from the herb with which my mom uses to cook.

    hmm…haven’t had it for a while now…time to put in a request for dinner :)

  • James – you have further piqued my interest. I am going to my grandma’s sister’s house for dinner this weekend, I will have to put in a request as well ;-)

  • i always thought it was khoai mon not mo. or maybe i am thinking of something else. but if it is what i am thinking then the soup is really good. i never had it in a dessert form before.

  • Angel Van – I had the hardest time id’ing this veggie. My aunt thought it was khoai mon too, but my co-worker says khoai mo. I’m pretty sure khoai mon is taro root, which is a paler purple.

  • In Florida, USA the conservancy and USDA regard Dioscorea alata to be invasive for its tendency to shade out trees(particularly in coastal hammocks.) I am growing some myself and have cooked just the tuber like you would any other yam. It was good (withour anything else) not great not bad just good. I look at it as a valuable staple crop.
    One question: I have read that uncultivated Dioscorea species can be bitter and even poisonous. Do you know if this is one of them or if you can tell a difference between a poisonous variety and a non-poisonous variety?
    Thanks, Ryan Barr

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