Chef Nobu Matsuhisa, of Matsuhisa in Los Angeles and Aspen and Nobu in New York City and London, uses shiromiso for this extremely delicate but intensely flavored dish.
3/4 cup shiromiso
1/2 cup sugar
1/4 cup sake
6 tbsp. mirin (sweet Japanese cooking wine)
1 lb. boneless sashimi-quality black cod
1. Put shiromiso, sugar, sake, and mirin in top of a double boiler and mix with a wooden spoon until smooth. Cook over simmering water over medium heat until fragrant, about 30 minutes. Remove from heat and set aside to cool.
2. Cut black cod into 8 equal pieces. Pour half of cooled miso marinade into a shallow dish, add cod, then pour remaining marinade on top. Cover with plastic wrap and refrigerate for 2–3 days.
3. Position a rack in center of oven about 8'' under broiler. Preheat broiler. Remove cod from marinade, arrange on a baking sheet, and broil until caramelized, about 10 minutes. Turn cod over and broil until fish flakes easily, about 3 minutes more.