Step 1

Combine ribs, ginger and onion in a large saucepan over low-medium heat, add enough water to just cover and simmer until ribs are tender (2 hours). Remove ribs with a slotted spoon (discard liquid) and set aside to cool. When cool enough to handle, cut into single ribs.

Step 2

Bring sake, soy sauce, mirin, sugar and umeboshi plum vinegar to the simmer in a wide saucepan over medium heat. Add ribs, reduce heat to low and cook until ribs are very tender and sauce is thick (18-20 minutes).

Step 3

For shiso salt, preheat oven to 160C. Scatter shiso over an oven tray and dry in oven until crisp (6-8 minutes), then coarsely crush with sea salt using a mortar and pestle.

Step 4

Serve ribs hot scattered with shiso salt.