Preheat the oven to 225 degrees Celsius.
Combine miso paste, rice vinegar, tamari and fresh ginger in a bowl. Add the diced fish and combine. Make sure that the miso marinade covers all parts of the fish. Set aside.
Quarter the boy choy and brush with hoisin sauce.
Put the bok choy in a oven safe dish and bake in the oven for five minutes.
Lower the temperature to 150 degrees and add the fish on top, drizzle the exceess miso marinade over the boy choy. Bake for another 5-10 minutes (until the fish is soft (approximately 50 degrees) and the bok choy has softened and become a little browned. Don't overbake, the bok choy should still be a little crunchy and the fish tender.
Take out of the oven and garnish with sliced red chili, scallion, cilantro, sugar snaps and furikake seasoning.