The Japanese sweet potato or 'satsumaimo' was one of those mystery veggies that came in my CSA box that I stored away in my potato basket for a couple weeks while I figured out what to do with it. Weeks went by and while extended family was here for Christmas, I thought 'what the heck, just roast it' (which is basically my go-to strategy for most mystery vegetables) and see what happens. It was a hit!
Roasted with just olive oil, salt and pepper, they were quite sweet with a 'carmelized' nutty taste. To me, they had a flavor similar to roasted chestnuts. Served with grilled pork loin, it made a nice pairing. They don't have a lot of water content so the roasted sections I cut almost had a homestyle french fry type texture. If you've ever tried to make sweet potato fries before, you know they have a higher water content and can sometimes turn into a soggy mess....not the case here.
Depending how much you read the fashion magazines or keep up with celebrity gossip, you may have heard that the Japanese sweet potato has recently become something of a hot item, being mentioned by people like Dr. Oz (sorry, think he's a quack) or by the actress Olivia Munn. Supposedly they are the 'secret' to her great looking skin due to the high content of hyaluronic acid in the vegetable. The more you know!
Japanese sweet potatoes are much smaller than regular sweet potatoes, with a dark red skin and a light sort of yellow interior. They are different from another Japanese yam called the 'Okinawan sweet potato' which has a white skin and purple interior.
The plant is actually a perennial vine that is quite attractive with heart shaped leaves and beautiful pink and white flowers as it is in the same family as morning glories. They are supposedly pretty easy to grow so this might be an experiment for next year's garden. You can plant in the Summer and harvest in the Fall. I watched this video and it seemed pretty straightforward.
This vegetable has tremendous importance in Japan due to some interesting history. In sort of an opposite tale from the Great Irish Potato Famine where potato crops failed and people bailed, the Japanese sweet potato was actually the hero that saved people from famine when rice crops failed in the Kanto region (where Tokyo is located) in the mid 1700's. One man, Aoki Konyo, a scholar of Confucianism and Western science showed that satsumaimo plants normally grown in the South could survive in the colder North. Because this knowledge was instrumental in alleviating the famine, Aoki came to be known as the "Potato God of Edo (the former name of Tokyo)". You can even find temples or shrines in this region dedicated to this special tuber.
Although I haven't tried yet, you can boil, steam or microwave these sweet potatoes with good results. There was even a charming post about making Japanese sweet potato 'Jenga fries' in a sweet, dessert version with cinnamon and a honey ginger dipping sauce - sounded yummy! Another post had a really interesting combo: Japanese sweet potato, avocado, and hard boiled egg.....odd but actually sounds quite good!
Good luck in your own experiments!