Combine all of the ingredients except for the water in a bowl, and mix until even. Add water, and briskly fold.
Grease a frying pan with oil (not listed in ingredients), heat the pan, then ladle the batter in spoonfuls onto the pan to make small coin-sized fritters.
Flip them over when they brown to fry the other side, then they are done when the onions become translucent!
They're tasty served with ponzu or okonomiyaki sauce.
Story Behind this Recipe
Once, I bought some sweet onions and natto when I'd forgotten that I'd already ordered them for delivery from my co-op, and so ended up with excess sweet onions and natto! I came up with this recipe as a way to use them up.
While they are frying, do not touch them. Even if they break apart while flipping them, they will stick back together by shifting the batter back in place with a spoon. You could pour in half the batter to make a large flat cake, but when I tried to pour all of the batter in, it was a challenge to flip it over. I recommend making 6-7 small flat cakes.