01 -
In a small bowl, whisk together white miso paste, mirin, rice vinegar, granulated sugar, soy sauce, and sake (or water) until the sugar dissolves and the mixture is smooth.
02 -
Arrange black cod fillets in a shallow dish or resealable bag. Pour the miso marinade over the fillets, ensuring each piece is thoroughly coated. Cover and refrigerate for 30 to 60 minutes for maximum flavor absorption.
03 -
Preheat the broiler to high. Position an oven rack approximately 15 cm beneath the heat element.
04 -
Transfer the marinated cod fillets to a parchment or foil-lined baking sheet. Broil for 10 to 12 minutes, until the surface caramelizes and the fish flakes easily with a fork. For deeper caramelization, continue broiling an additional 1 to 2 minutes, monitoring closely to prevent burning.
05 -
Plate the broiled cod fillets. Garnish with fresh lemon wedges and chopped green onions, if desired. Serve immediately.