If using sardines with the heads still attached, remove the heads and fins, and scoop the innards.
It'll look like this after you finish. Thoroughly wash out any bloody parts down to the center spine. If you lightly scrape off the scales, it'll come off easily.
Place the finished side facing up in a pot, cover with a drop-lid, add the ● water and vinegar, and simmer for 10 minutes. If you don't have a drop-lid, use a sheet of aluminum foil. Be sure to cook on low heat!
Discard the simmering juices from Step 3 and add the other seasoning ingredients. Add the umeboshi (pound the flesh with your palsm), the pit, and the ginger. Cover with a drop-lid and simmer for about 20 minutes, and it's complete.
Story Behind this Recipe
I had some reasonable sardines, but I wasn't sure what to do with them with the cooking ingredients I'd bought. My mother taught me how to make this Japanese dish from these ingredients.
Sardines fall apart pretty easily, so simmer on low heat. If you are put off by the idea of preparing fish, buy filets.