1/3 cup sake
1/3 cup mirin (Japanese sweet rice wine)
3 tablespoons soy sauce
1/4 cup packed brown sugar
1/3 cup miso paste
4 (4 ounce) fillets fresh sea bass, about 1 inch thick
2 tablespoons chopped green onion
Whisk together the sake, mirin, soy sauce, brown sugar, and miso paste in a bowl to make the marinade. Place the sea bass in a large sealable plastic bag and pour the marinade over the sea bass. Chill in refrigerator 3 to 6 hours. Arrange the fillets on a baking sheet. Discard the marinade.
Preheat the oven’s broiler and set the oven rack about 6 inches from the heat source. Prop the oven door to remain slightly ajar.
Bake the sea bass under the broiler until the fish flakes easily with a fork, 7 to 9 minutes. Sprinkle with chopped green onions to serve.