Broiled Cod With Sesame-Miso Sauce

¼ cup sesame seeds
¼ cup miso, preferably red
2 tablespoons sugar (or 1 tablespoon each sugar and mirin)
1 tablespoon soy sauce, or to taste
1 ½ to 2 pounds cod, in 1 or 2 fillets, preferably of equal thickness throughout
Extra virgin olive oil or neutral oil like corn or canola, as needed
Pinch cayenne

4 servings

Place oven rack 4 inches or less from heat source. Heat broiler. In a small dry skillet over medium heat, toast sesame seeds, shaking pan until they color slightly. Grind to a powder in a spice or coffee grinder or use a mortar and pestle.
Use a whisk to combine seeds with the miso, sugar and soy sauce. If the mixture is more like a paste than a sauce, thin it with a little water, mirin, or more soy sauce. Taste, and adjust seasoning. (Sauce may be covered and refrigerated for up to 2 days. Stir before serving.)
Brush fish with oil, then sprinkle on a bit of cayenne. Place fish on a baking sheet, preferably nonstick, and put in broiler. Cook, rotating sheet once so fish browns evenly on top and is cooked through, 6 to 10 minutes. The fish is done when the point of a thin-bladed knife inserted into thickest part meets a little resistance. Drizzle sesame-miso sauce on top, and serve.

20 minutes