On lists of Nagoya foods, hidden among the more famous chicken wings and miso katsus, is a mysterious little confection that resembles a clump of sticky, pale yellow boulders. It’s called oni manju (鬼まんじゅう), the demon dumpling, supposedly for its resemblance to the spiky end of the demon’s metal club. Oni manju is made with just three ingredients — sweet potatoes, sugar, and flour — and unlike most dumplings isn’t filled with something delicious, it’s just little cubes of sweet(er) potato, all the way through. It’s a curious little dessert. In our house, two out of three people love them. But, of course, one of those people is three years old and responds to most offers of new food with, “is it あまい?” Yes, Anna, it is sweet.
Since it was on most of those lists, I figured it would be everywhere in Nagoya. A little oni manju shop on every corner, or something like that. In fact, it is not. On our first visit to Nagoya, we ended up having to ask the Takashimaya food floor concierge (yes, this job exists), before finding a tiny selection of them in the back of a Japanese sweets shop. When we went back, I had done a little more research, and we took the subway out to a neighborhood called Kakuozan to visit a shop called Baikado (梅花堂) that’s famous for oni manju. The shop was empty except for a small glass case of sweets that were distinctly not oni manju, and a handwritten sign on the counter, 鬼まんじゅう 1個 134円 — oni manju, $1.25. We put in an order for three manjus, and were told the next batch would be ready in an hour or so. We wandered around Kakuozan for an hour — it’s lovely, I recommend it — and ate our dumplings on the Shinkansen that afternoon.
By that point, I’d been making them at home for a while, but (of course) Baikado’s were far better than mine. The main difference was, and still is, the candy-like coating that envelopes and binds the potatoes together. When done right it looks as if some kind of shiny plastic resin has been melted over and around the potato cubes, almost like the fake foods in glass cases outside Japanese restaurants. My better attempts have the same taste and texture, but only once have I achieved that perfect plastic-food look. And if you don’t add enough sugar and flour, or don’t mix everything properly, it comes out more like a clump of floury potatoes desperately clinging to each other.
The most important ingredient, practically the only ingredient, is sweet potatoes. In America, sweet potatoes are brown-skinned, orange-fleshed, and used primarily in somewhat off-putting desserts served at Thanksgiving. (One particularly grotesque incarnation has marshmallows melted over the top of baked, spiced potatoes.) In Japan, sweet potatoes — called Satsuma imo after the old name for Kagoshima, where they’re grown — are usually reddish-purple on the outside, white or pale yellow on the inside, and noticeably less sweet than the American ones. In the winter, you can buy roasted sweet potatoes from the back of a little truck that drives slowly around blaring a song about potatoes roasted over hot stones (♪yaki-imoooo, iiiishiiiiiii yakiiiiiii-imo♪). They’re also made into fancy desserts, fried in tempura, and turned into shochu, the most wonderful beverage in the world.
And in Nagoya, they’re cut into little cubes, stuck together with a floury-sugary paste, and steamed to make oni manju. This being a dessert, you could probably make it with any type of sweet potato, even the American ones, but what I use is something sold as “Korean yams,” which looks and tastes pretty much like a standard Satsuma imo. An orthodox oni manju is made with peeled Satsuma imo and white sugar, so that the final dumpling is an unexciting, pale yellow monochrome. You can also leave the skin on, which I prefer, to add some color (, or get all crazy and use brown sugar for a mottled, somewhat sweeter version called a black oni manju (黒鬼まんじゅう).
INGREDIENTS (for 4 dumplings)
- 180g sweet potatoes — See above, but preferably Japanese sweet potatoes that are white or pale yellow inside and reddish-purple outside.
- 50g sugar — For a standard oni manju, use normal white sugar. You can also use brown sugar for a slightly sweeter, more visually interesting version.
- 75g flour — I use the same pastry-ish flour as I use for most dishes.
- Peel the potatoes. Or don’t, if you want the skin-on version.
- Cut the potato(es) into small cubes, a little less than 1cm on each side.
- Put the potatoes in a large bowl, add the sugar and an optional pinch or two of salt, and mix.
- Let the sit for about 15-20 minutes. The sugar will, somehow, mysteriously, melt into a kind of syrup due to… um… well, it just does.
- While the sugar is melting, prepare little squares of parchment paper for the dumplings to sit on.
- Thoroughly mix the potatoes and sugar.
- Add a little bit of water, maybe 1.5 tbsp, and thoroughly mix again. The potatoes should be coated in sticky sugar syrup.
- Add the flour and mix until you have a smooth goo surrounding your chunks of potato. You want to make sure there are no chunks of flour.
- Form the sticky potato goo into small dumplings. I usually use a 1/4 cup measure to scope the potatoes out and form the shape. Put each dumpling on a piece of parchment paper. Make sure you get ALL of the sticky flour-sugar out of the bowl and onto your manjus, since it’s the only thing that’s going to hold them together.
- Heat a pot of water and prepare some kind of steamer (I use a double-boiler). Wrap the lid in a tea towel to prevent water droplets from forming and dripping onto your dumplings.
- When the water is boiling, put the dumplings into the steamer, and steam on medium-high heat for about 17 minutes.
I usually let the dumplings sit on the counter for a while until they’re room-ish temperature before eating them, though they are also delicious hot out of the steamer.