Sweet potatoes

Try the Japanese version

By
November 25, 2008

No matter how many times I remind myself that the sweet potato and the yam are not the same tuber, I still hesitate when asked to explain the difference. It’s a problem of nomenclature: Nearly all of the “yams” that we come across in North American markets are actually sweet potatoes. And sweet potatoes aren’t related to potatoes.

Confused? The sweet potato is a New World native, its popularity spread by Columbus. True yams, on the other hand, are giant tubers that originated in Africa thousands of years ago; they aren’t commonly available here.

The plants belong to different botanical families, but they do share some physical and flavor similarities. Today we tend to think of “the orange ones” as yams and “the white ones” as sweet potatoes, when they are both simply different varieties of sweet potato.

Currently, China grows more sweet potatoes than any other nation. Most of the Chinese crop is exported or sold as feed; because of this livestock connection, sweet potatoes were traditionally consumed by society’s poorest. War-induced famine also kept the Asian variety of the sweet potato hidden in homes.

japanese sweet potatoes
Japanese sweet potatoes are red on the outside and creamy white on the inside.

But over the last 10 years or so, the sweet potato has been gaining in popularity as chefs and restaurateurs try to put a new spin on this healthy vegetable. Both here and in Japan, many izakaya lounges not only serve tempura-fried sweet potatoes but also pour shochu, a liquor sometimes distilled from sweet potatoes. (The drink is called soju in Korea.)

During the fall and winter months in Japan, bakeries mix them with sugar, cream, and eggs to make sweet cakes and pies. Street vendors also offer them, steamed simply in their casings, to fight the chill of cold winter days.

I recently came across some Japanese sweet potatoes at my local farmers’ market and was curious to see how they differed from the usual American sweet potatoes. Not to be confused with purple-fleshed Okinawan sweet potatoes, these were the white-fleshed Satsuma-imo variety.

Since they looked very similar to our common red-skinned sweet potato, it wasn’t until I began peeling them at home that I noticed the difference. Once exposed to the air, Japanese sweet potatoes quickly begin to turn brown. With a bowl of cold water at hand, I swiftly sliced and immersed them. They were also incredibly starchy and dry.

Stateside, Japanese sweet potatoes are a fleeting fall crop, so grab some when you see them. If you like their delicate, sweet taste, go back for more and store them loose in a cool drawer or cupboard for up to a few weeks.

For mashing, I found that roasting them dried them out too much. A quick steam in the microwave was a faster and tastier alternative. Better yet, peel, cube, and simmer them in water like you would russets. Or fry them, per Mark Bittman’s suggestion.

Substituting Japanese sweet potatoes for common sweet potatoes is possible, but you might need to add a little more liquid in recipes. Their dry nature and mild chestnut flavor make them a popular substitute for chestnut purée. In our house, we ate them mashed, au gratin, and roasted. My teenage son’s favorite preparation, however, was as Japanese sweet-potato chips.

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1. by j hersh on Dec 3, 2008 at 12:52 PM PST

a sweet potato poked a few times with a knife and microwaved makes a terrific, quick, and healthy breakfast. the only downside is that the skin doesnt taste great cooked this way, but it’s worth it to have a sweet potato that only takes a few minutes (depending on size, i’d say an average of 4 minutes) to prepare. jh

2. by vesperlight on Dec 20, 2008 at 11:38 PM PST

I lived in Japan as a Navy brat in the late 1960s. I have fond and intense memories of the sweet potato man, who came down our street at dusk in early winter. He pushed a hand-cart with a charcoal oven and a steam whistle. When we heard the whistle, our mother would hand us money and we would run out into the cold night, following the sound of the whistle until we found him, then run home, juggling the hot potatoes (wrapped in newspaper). She split them, mashed them lightly with a fork, and put margarine on them. They were wonderful.

3. by angela on Jan 6, 2010 at 10:47 AM PST

Standing in the grocery yesterday I paused to consider whether to buy sweet potatoes or yams, is one healthier, presumably the yam with it’s rich color? I purchased the sweet potatoes for the mild flavor, purported health benefits and because they are my favorite... I’ll make one for lunch today! Great web site by the way!!

4. by anonymous on Mar 27, 2010 at 10:20 AM PDT

I bought Japanese Sweet Potatoes at Whole Foods Market, in Atlanta GA. they are the best sweet potatoes I have ever tasted. Delicious.

5. by anonymous on Jul 23, 2010 at 1:24 PM PDT

I lived in Japan for most of the 1960s and part of the 1970s, I was in the air force at Yokota AB, west of Tokyo. The sweet potato man came past my house in the fall with his goodies packed in hot gravel to maintain warmth. My Japanese wife would hear his bell and shouts of, “O-imo” and purchase several. We never added butter as the taste stood by itself and needed no help.

Now they are available from my local Asian market and I but them often. We wrap them in foil and cook them in a small convection oven. We would never dream of ruining their great flavor by adding anything. Forget the butter!

6. by anonymous on Feb 20, 2011 at 4:42 PM PST

I found Japanese Sweet Potatoes at Uwaijmaya market in our area.

7. by anonymous on Mar 9, 2011 at 1:49 PM PST

Whole Foods in Duluth, GA had some wonderfully delicious Potatoes. Try them for a fun change from the orange ones we’re accustomed to.

8. by Adelaide Smith on Mar 18, 2011 at 8:13 AM PDT

This sounds like a wonderful food but, where can I find Japanese sweet potatoes?

9. by Naira (Nay) on Sep 13, 2011 at 11:34 AM PDT

Luckily I found this article regarding sweet potatoes. Yes, I agree with all comment concern about this delicate flavor of sweet potatoes. Recently I am interested to promote it more in more since in my area there’re lots of farmers keep asking me to help them to find market for their sweet potatoes. I’ve been able to market them but the local market sometimes can’t absorb all their harvest. I really would like to find buyers out side of country to help farmers in order they can sell the harvest regularly, But I have no experience to do so. For additional info, there are actually lots of varieties of sweet potatoes besides the above picture, and sometimes different farmer at different area called certain potatoes for the same type, e.g.: 1.Japanese sweet potatoes-- has white skin and yellow inside, Red skin with white inside, Red skin with orange inside, Red Skin with Yellow inside, White skin with Yellow inside, Purple skin with purple inside, Purple skin with Purple and white stripe inside, and so on. each of them has it own unique tasty-flavor.

So, if anyone or yourself would like to help me out to market this delicate and nutritious sweet potatoes, or you know someone who’s searching for sweet potatoes, please give me a hint. I can be reached on my e-mail address : nin_pahyung@hotmail.com.

Thanks and Warmest Regards,
Nay.

10. by anonymous on Nov 22, 2011 at 9:11 PM PST

Back when I didn’t know a whole lot about food, I thought that these were basically the same as the orange-fleshed ones, so I bought them for a sweet potato pie recipe I wanted to try for the big family Thanksgiving thing. Needless to say, there were definitely plenty of adjustments I could have made, but I was way too inexperienced to know better. The pie looked kind of weird and most at the gathering where a big afraid to try it, but it tasted pretty good. Not exactly like your typical sweet potato pie, but pretty good. My grandma loved it, though, so that’s a plus.

11. by anonymous on Dec 21, 2011 at 7:21 PM PST

I bougnt my Japanese Sweet Potatoes at Whole Foods just a few days ago. I prepared them for dessert to follow my butternut squash soup. I put them in my rice cooker on steam then pureed them until smooth. I put a little brown sugar on my and brown sugar and butter on my husband’s. I froze the unused portion to make easy desserts for the rest of the week. I like this version of sweet potato but I think I like traditional sweet potatoes better.

12. by anonymous on Apr 29, 2012 at 3:58 PM PDT

IMO it is a mistake to peel the JSW. They are great baked in their skin. Eating them like this reveals their character. They are also great whipped with a little butter.

13. by Rupricht on Jun 7, 2012 at 3:12 PM PDT

I buy mine at the Cobb International Market on Spring Road in Marietta, just past Cumberland Mall. These are unbelievably good cut into 1.5 inch chunks, dusted with Good Season’s Dry Italian Salad Dressing seasoning and olive oil and roasted @425 - 450 degrees or until the edges are brown. Actually going to bake two whole tonight, slice them into rounds and fry them in very shallow oil.

14. by Raederle Phoenix West on Sep 27, 2012 at 12:14 PM PDT

I just ate a big bowl of steamed Japanese sweet potatoes out of my pressure cooker. Took about five minutes to warm up the machine, six minutes to cook at high pressure, and the result is absolutely delicious, soft and flavorful. I’m very pleased with them. Thanks for this article -- I wasn’t convinced they were really a sweet potato and not a yam, but after poking around the internet I see that they really are a sweet potato. I have free recipes on my website if you’re interested, although, none involve sweet potatoes (or yams, for that matter) currently. Lots of love & smiles! ~ Raederle

15. by Baking Scientist on Mar 20, 2013 at 11:39 PM PDT

Thank God that Japanese sweet potatoes are available at our supermarkets. I love sweet potatoes and as Singaporean Chinese, we love to boil them together with green beans and rock sugar to make a dessert. But I agree that it is a very healthy food, and needs no fuss in preparation, and tasty on its own without the need to add anything :)

16. by Al Bracknell on Jun 16, 2013 at 1:05 PM PDT

Bought a very large Japanese sweet potato recently at Whole Foods Birmingham Al. I peeled, cubed, and tossed with melted coconut oil., sea salt, cinnamon, and Balti seasoning from Penzeys. Roasted covered thirty minutes on 400 and then 15 minutes on a cookie sheet convection mode. They were incredibly moist and flavorful!

17. by anonymous on Nov 18, 2013 at 5:56 PM PST

I only eat them steamed - very very delicious and healthy espcially for those with health problem - not sure about people with diabetes cos these are really sweet potatoes.

18. by anonymous on Nov 26, 2013 at 12:25 PM PST

Could some one send me information on growing and ordering the Japanese sweet potato bigcapton77@yahoo.com

19. by anonymous on Jan 20, 2014 at 2:08 PM PST

Spray with EVOO and bake at 400 deg for 60-90 minutes depending on the size of the sweet potato. The skin comes out with a deliciously carmelized flavor and texture. We have been eating these 2 to 3 times a week when available at the farmer’s market here in California.

20. by anonymous on Feb 24, 2014 at 12:03 AM PST

Here in California (SF Bay area) most Asian grocery stores (Indian, Vietnamese, Thai etc.), have them all year round and pretty cheap.
The Japanese ones are far superior in taste to the the others and cost about the same so it’s “no contest” as to which ones I buy.

21. by anonymous on Apr 15, 2014 at 2:23 PM PDT

Stumbled upon these at our local food co-op in Bisbee, AZ today. Wrapped one tightly in four paper towels, doused the whole thing in water, and popped it into the microwave (low-powered office kitchen model) for seven minutes. Noshing on it skin and all as an absolutely delicious mid-afternoon snack :)

22. by anonymous on Jul 28, 2014 at 12:30 PM PDT

I sliced them up with the skin on, sliced up a couple small yellow squash and fired in a little olive oil and sea salt and they were delicious.

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