Bring sake and mirin to a boil. Turn the heat down and slowly add white miso until completely dissolved. Turn heat up and add sugar. Mix until dissolved.
Remove from heat and cool to room temperature.
Method:
Place black cod in a non-reactive dish and cover with Miso Glaze. Refrigerate for 1 or 2 days.
Preheat oven to 400°F. Lightly wipe off excess Miso Glaze from fillets. Place the fillets on a roasting pan and bake in oven for 10 minutes. Blanch baby bok choy for 1 minute and then cut in half. Heat sesame oil in a medium sauté pan over medium heat. Then add vegetables (including bok choy) and sauté for 1 minute. Remove from heat and add soy sauce.
To Serve:
Arrange the banana leaves on each serving plate, followed by the vegetables and top with black cod fillet. If not using banana leaves, garnish with orchid (optional).