Step 1
Preheat oven to 425°F. In a small skillet, melt the butter over medium heat. Add the ginger, garlic and sesame seeds and stir 30 seconds. Stir in the panko and miso and season with cayenne and black pepper.
Step 2
Season fish lightly with salt and pepper and arrange on a sheet pan, tucking the thin edges of the fish under so the fish will cook evenly. Top with the miso crumbs and bake just until fish is cooked, about 8 minutes. Sprinkle with the scallions and serve.
