Wednesday, April 16, 2008

Okinawan Sweet Potato Soup

The Okinawan sweet potato (beni imo) is an excellent source of antioxidants and dietary fiber. Outside of Japan, this sweet potato is primarily grown in Hawaii.

I had my first taste of this delicious purple beauty when I moved to Hawaii in 1993. My family boils them and then peel the paper-thin skin off to eat as a snack. I especially love mine with a little pat of butter.

I cut it in half when still raw to show you just how beautiful it is! It's very similar to the Southeast Asian yam called ube in the Philippines and khoai mo in Vietnam. I had a very tasty vegan khoai mo soup at a temple in Vietnam, so I decided to make a similar soup when I saw these sweet potatoes at the Asian market. The soup turned out to be a bit sweet for my liking (unlike canh khoai mo) because I really don't have a sweet tooth at all, but those of you who favor sweet and savory dishes would love it!

Okinawan Sweet Potato Soup
(Yields 4 Appetizer Portions)
  • 1 tbsp extra virgin olive oil
  • 1 tbsp butter
  • 4 stalks scallion, chopped
  • 2 cloves garlic, crushed
  • 1 big Okinawan sweet potato, peeled & diced ½ inch
  • 2 cups chicken/vegetable broth
  • 2 cups water, more or less to desired consistency
  • ¼ cup unsweetened Thai coconut milk
  • Sea salt & freshly cracked black pepper to taste
  • Chopped cilantro leaves to garnish

Melt butter in a saucepan with a drizzle of olive oil. Sweat scallion and garlic over low heat until soft and almost golden. Add the potatoes, broth, water and salt and bring to a boil. Lower heat and simmer for 20 minutes or until potatoes are tender. Add coconut milk and take off heat to puree with hand blender until smooth. Adjust seasoning and add black pepper and cilantro leaves. Serve hot or chilled.


Marija said...

This looks so yummy! Did you try making those potatoes into puree? I bet it would look beautiful.

Tia Nguyen said...

Thanks, Marija! I've only had these potatoes boiled and eaten with butter, so this is my first time experimenting with them. I've seen them pureed, mashed and in pies and the result have always been stunning because of the brilliant color!

DVQ said...

You referred sweet potato as in Khoai Mo in Vietnam is not correct. Sweet potato is Khoai Lang. The one in the photo is purple sweet potato (sweet potato can be found in many colors: white, yellow, purple). Khoai Mo in Vietnam is Taro (it can comes in 2 colors: white and purple, it has several types/ shapes/ sizes). And Canh Khoai mo in Vietnam is made with purple taro or white taro, not with purple sweet potato. Sweet potato is not used for making Canh (vietnamese soups)

Tia Nguyen said...

Hi, DVQ. Thank you for your comment—I always enjoy a good discussion about food! If you reread my post, I did not refer to the Okinawan sweet potato as khoai mo. This post is titled: Okinawan Sweet Potato Soup, not Canh Khoai Mo. Although sweet potato is not commonly used in Vietnamese soups, it is used in soups in other parts of the world. I would love to write my blog fully in both English and Vietnamese versions, but with limited time, I’m only able to provide my content in English for now. However, here is a simple breakdown of the three plants in English and Vietnamese, along with their scientific names(danh pháp khoa học) for clarification. If you feel more comfortable discussing this in Vietnamese, please feel free to contact me via e-mail and I will reply in detailed Vietnamese for further clarification of their culinary uses. Thank you for stopping by!

Vietnamese name: Khoai mo
English name: Purple yam; more commonly known by the Filipino name of ube
Scientific name: Dioscorea alata

Vietnamese name: Khoai mon
English name: Taro
Scientific name: Colocasia esculenta

Vietnamese name: Khoai lang
English name: Sweet potato
Scientific name: Ipomoea batatas

Ama said...

@dvq - maybe you should actually read the whole post before making such comments. you are also wrong when you said khoai mo is taro. khoai mo is a yam and khoai mon is taro. also, the okinawan sweet potato is different from the other types of purple sweet potatoes around the world. do your research.

DVQ said...

TiaNguyen, I did read your whole post and I did enjoy reading it. Maybe I misundestood the notion of your sentence "(Okinawan) It's very similar to the Southeast Asian yam called ube in the Philippines and khoai mo in Vietnam" because I find sweet potato and yam different. Sweet potato is not related to yam at all (but it's often mistakenly named or called yam). And in that sense, just wanted to make a note that sweet potato is not used in making Canh in Vietnam but yam is (khoai mo).

Re:the names:I know Khoai mon and Khoai mo are different. And admittedly I messed up with the names in English when i posted the previous comment. Khoai Mon is Taro (or gabi in the Philippines). Khoai mo is yam (or ube in the Philippines).

Anonymous said...

nor10,I first bought these potatoes not knowing anything about them,found your web sight,made this recipe with a few changes to suit my taste.fanflipin'tastik! Im really surprised more post were about what this thing is called and its lineage.I for one enjoyed "the purple tuber".

Anonymous said...

Hello Tia Nguyen and gentle readers,

Purple yam (or purple names)is called "khoai ngo.t" in south VN.
White yam (names)is called "khoai mo+~".
There is also a yellow names that is also called "khoai mo+~ ga`".
Purple names tastes better than the rest and are more expensive than the other two.


Yen said...

Hi Tia - lovely blog you have! I'm wanting to make Sweet Potato Haupia Pie (using these Okinawan Potatoes). Perhaps it was already clarified in an earlier comment, but just to be sure I'm not confused, is there an actual Vietnamese name for these potatoes or not? And if not, where would you suggest I find them? Many thanks in advance for your response!

Tia said...

Thanks, Yen. Okinawan sweet potatoes are called khoai lang tím in Vietnamese. Make sure the skin is tan and the inside is purple as the ones that are purple on the outside are actually white on the inside. And, of course, they do not taste quite as nice as the Okinawan sweet potatoes. :) I've seen them in Vietnamese and East Asian markets labeled as Japanese/Okinawan/Hawaiian sweet potatoes, but they are not consistently stocked. Good luck and thank you for stopping by. :)

Anonymous said...

I noticed that the ones at the supermarkets sometimes are bitter on the inside. You can buy directly at the farm from Hawaii at the site below:

ben said...


So is the purple :
“ube Asian Yam”
in fact the same as the
okinawan sweet potato?

or are they different?

Tia said...

They are different. The Okinawa sweet potato is a sweet potato and the ube is a yam.

Josie said...

Hi! I accidentally bought these at our local Asian grocers because they were 75cents each and I thought they were sweet potato haha so after cutting them up and putting them in the slow cooker hoping to god they'll be something worth making a soup out of!! I googled to find out what they were then tried to find out recipes for a soup using them :-) so Thank You!!! :-)