Add the ○ ingredients in a pot, and bring to a boil.
Place the sardines in the boiling sauce, cover with an otoshibuta drop lid, and simmer for about 20 minutes over medium heat.
When the sauce has reduced to about 1/3, it's done.
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Story Behind this Recipe
I love the combination of sardines and umeboshi. Umeboshi makes the bones and meat tender. The backbone is hard to eat, but you can eat the small bones.
If you have pickled red shiso leaves with umeboshi, add to the simmer. It will be tasty as well. After simmering the sardines, umeboshi and red shiso leaves adds a concentrated flavor, but it goes well with rice.