Cut the bell peppers in half lengthwise and remove the seeds and stems. Finely chop the onion.

In a bowl, mix the ground pork, onion, white dashi, sake, and potato starch until sticky, then divide into 8 portions.

Dust the inside of the bell peppers with potato starch and stuff each with the pork mixture.

Heat vegetable oil in a frying pan over medium heat and place the stuffed peppers meat-side down. Cook for 2 minutes.

Flip the peppers, reduce to low heat, add water, cover, and steam for 7 minutes.

Pour the sauce ingredients over the peppers and simmer until the sauce is reduced. Serve.