Combine miso, sake, mirin, soy sauce, oil, and sugar in a bowl and whisk them thoroughly. Evenly coat all sides of the cod fillets with the marinade. Place the fillets in a zip-top bag or a sealed container. You can proceed to the next step immediately, but for best flavor, marinate for about 30 minutes or up to 2 days.
4 Cold Fillets, 1/4 cup White Miso, 2 tbsp Mirin, 2 tsp Soy Sauce, 1 tbsp Vegetable Oil, 1/4 cup White Granulated Sugar, 1 1/2 tbsp Sake
Place the marinated cod on a roasting pan lined with parchment paper.
Press the "Start Cooking" button, and the oven will start preheating. Once preheated, insert the roasting pan into Level 2.
Using oven gloves, carefully remove the cod from the oven.