Combine the minced onion, meat, egg whites, panko, 1/4 teaspoon of salt, and pepper, and mix until it becomes sticky. You'll use the egg yolk when serving.
Make into 12 round patties (see in the Helpful Hints), and cook both sides golden brown in a vegetable oil-covered frying pan .
Add the sake, then add the sugar, mirin, and soy sauce. Simmer while turning the patties over.
Story Behind this Recipe
I wanted a sauce with a strong flavor that went well with rice or alcohol.
If you use 200 g of chicken minced meat and 100 g of drained tofu you get a light, delicious taste. You can also add shiitake mushrooms or leftover simmered hijiki seaweed. If you lightly dampen your hands it's easy to make the round patties. You might feel that the amount of sauce is excessive, but while simmering it develops quite nicely.