Preheat broiler. Broil peppers and tomatoes on a foil-lined baking sheet 5 inches from heat, with oven door partially open, about 5 minutes on each side or until blistered. Place in a heavy-duty zip-top plastic bag; seal and let stand 10 minutes to loosen skins. Open bag, and allow to cool. Peel peppers and tomatoes; remove and discard seeds and stems from peppers.
Reduce oven temperature to 400º. Cut off pointed end of garlic head; place on a piece of aluminum foil, and drizzle with 1 tablespoon oil. Fold foil to seal. Bake at 1 hour; remove and allow to cool. Squeeze pulp from garlic cloves, and place in a food processor with peeled peppers and tomatoes. Pulse until roughly chopped and a chunky consistency.
Melt butter in a large saucepan over medium heat. Add onion, and cook until soft and just beginning to brown, about 8 minutes. Add chopped raw garlic, and cook 1 minute more. Stir in chopped pepper mixture.
Add stock and vinegar, and bring to a low boil. Simmer, uncovered, 30 minutes or until sauce has a thick, stew-like consistency. Season with hot sauce, salt, and pepper. Stir in mint and next 3 ingredients.
Combine flour and cornmeal in a shallow dish. Season catfish with salt and pepper, and dredge in cornmeal mixture, pressing to adhere. Heat remaining 4 tablespoons oil in a large skillet over high heat, and fry catfish in batches, 3 minutes per side or until cooked through. Transfer to a paper towel-lined baking sheet, and place in a 200º oven to keep warm.
Place rice on a large serving platter. Remove fish from oven, and arrange on top of rice. Spoon sauce over fish and serve remaining sauce alongside. Season with salt, pepper, and hot sauce to taste.