In a small saucepan, bring the Mirin (3 tablespoon) and Sake (3 tablespoon) to a boil.
Whisk in the White Miso Paste (1/2 cup) until dissolved.
Add Granulated Sugar (1/3 cup) and cook over moderate heat, whisking, just until dissolved.
Transfer the marinade to a large baking dish and let cool. Add the Skinless Black Cod Fillet (7 ounce) and turn to coat. Cover and refrigerate for an hour.
Place the rack 6-inches below the broiling element in your oven. Preheat the broiler on high heat for 10 minutes. Line a baking sheet with foil and a little Vegetable Oil (to taste). Scrape the excess marinade off the fish and place it skin side down on the baking sheet.
Broil it for 10 minutes or until the top is caramelized.
Transfer to plates and serve with Pickled Ginger (to taste). Enjoy!