Mince the umeboshi plum (remove the seed). Filet the fish. Cut off the head and tail and remove the innards. Rinse with salt water and cut it into bite sizes.
Mix all the ingredients in a pressure cooker and let it come to a boil. Add the fish and cover the pressure cooker with a lid and start (the photo shows three fish worth).
Cook for 15 to 20 minutes and let sit until it cools down. Then it is ready (the photo is after pressure cooking for 17 minutes).
If plated on a 20cm diameter dish, it'll look like this.
[9/13/07 edit] I used the pressure cooker over a gas stove. I cook for 20 minutes so there's only a little bit of broth left. If you cook for 15 minutes, there will be more sauce, but the bones will be soft and ready to eat. Adjust the time depending your pressure cooker.
[9/20/07 edit] I received feedback from some users who noticed that the bottom on the pot got burnt. To avoid this, adjust the recipe by adding less sugar, more sake or water, reduce the cooking time.
Story Behind this Recipe
It's my family's favorite recipe.
An umeboshi plum is enough to get rid of the fishy smells. Use 2 if you want a stronger umeboshi taste. If you like it sweet and salty, add 1 tablespoon each of sugar and soy sauce. If you prefer it light, reduce the amount of sugar. You can also double the ingredients. I was selected as a monitor for Takara brand's "Cooking Sake" and found the taste to be much richer when I started using it.