Two to 3 days beforehand, make the miso marinade and marinate the fish. Refigerate or Freeze.

For the marinade: Put ginger, garlic and sesame oil in measuring cup. Microwave in 15 second bursts. While hot add miso paste and mix to a paste. Mix in the sake or wine, mirin or vinegar and sugar. Microwave again until hot until sugar dissolved. Cool to room temperature.

Pat the black cod fillets thoroughly dry with paper towels. Slather the fish with the miso marinade and place in a non-reactive dish or bowl and cover tightly with plastic wrap. Leave to marinate in the refrigerator for 2 to 3 days.

For the fish: Preheat broiler on high. Heat a cast iron skillet over high heat on the stovetop with a little oil. Dont rinse fish. Place the fish skin-side down on the pan and cook 4 minutes. Dont flip. Brush top (flesh side) with sweet soy syrup. Transfer skillet to the broiler for 5 to 10 minutes, until well browned and fish is opaque and flakes easily.