Onigiri with simmered kombu and umeboshi fillings

Reconstitute the kelp in water for 15 minutes until soft and flexible.

Pat dry and slice into thin ribbons two to three inches long; it is sticky once cut.

In a saute pan combine the kombu with half a cup water, one tablespoon rice wine vinegar, three tablespoons soy sauce and one tablespoon each mirin and sake.

Bring to a simmer over medium heat and cook about 10 minutes, adding a big tablespoon of sugar, until most of the liquid evaporates into a thick sauce (about 7 to 10 minutes).

Sprinkle generously with sesame seeds, set aside and cover.

Pit the umeboshi by squeezing them, mash with a fork and chop a little.

Wash the rice thoroughly with about a cup of water at a time, sloshing to rinse off the starch, until the water runs almost clear.

Cook in a pressure cooker with one and a half times its volume of water, high pressure for seven minutes, rest five, then release the pressure with the valve.

Spread the rice on a sheet pan and, while hot, drizzle with two tablespoons rice wine vinegar, one tablespoon sugar and one teaspoon salt; mix gently without mashing so it stays fluffy.

With wet hands, make a disk of rice, add a few pieces of filling, top with another disk and close the edges.

Pat the plum-filled ones round, like a burger patty; for triangles, hold flat with one hand and press down with a cupped hand on top.

Wrap a strip of seaweed around the bottom of each triangle as a handle.