1. In a blender, puree the onion, garlic, and sesame seeds with the brown sugar, allspice, thyme, nutmeg, 1 teaspoon of the salt, the black pepper, cayenne, oil, and vinegar. Heat the broiler. Lightly oil a broiler pan or baking sheet.
2. Sprinkle both sides of the catfish fillets with the remaining 1/4 teaspoon salt and put them on the prepared baking sheet, skinned-side down. Spread the spice mixture over the fish in an even layer.
3. Broil the fish, about 6 inches from the heat if possible, until well-browned and just done, about 5 minutes for 3/4-inch-thick fillets.
Fish Alternatives: Though catfish is lean and firm, those qualities aren't imperative here. You can use fillets of a different nature, such as bluefish, red snapper, or wolffish.
Wine Recommendation: Make your beverage choice as simple and casual as this dish--and look for something that can take the heat. Try either a white zinfandel, a rosé, or your favorite beer.