Batter:
1 cup cake flour
1/3 tablespoon baking powder
2 eggs
1 medium potato, grated to paste
1 glass of bouillion (dashi if you can get it)
Enough additional hot water to make it a sticky batter a little thicker than clotted cream consistency
Mix the batter and put it in the fridge to rest. Then add a quarter of a small cabbage, finely minced. Then add more cabbage. No, really. You can never have too much cabbage.
Then the rest. Green onions are good. So is canned sweetcorn. Shrimp if you like. Pickled ginger, lots.
Heat up a frying pan brushed with oil, low heat. Pour a thick pancake or two on it. Put thin slices of pork belly (can be smoked) on top, and cover with a lid. Check after a minute or two or three, to see if the bottom's solid enough to flip it with two spatulas. If so, do that. Once the other side's crispy, flip it again and again and again. Until it's springy rather than a spongy mess.
Okonomiyaki sauce and kewpie mayo are good, but ketchup will do in a pinch ;)
Note to self: this amount makes Far Too Much For One Person. Next time, use two frying pans at once.