Thaw fish, if frozen. Rinse fish; pat dry. Place fish in a shallow dish. For marinade, in a small bowl, stir together tequila, lime juice, jalapeno pepper, cumin, and garlic. Pour marinade over fish. Cover and marinate in the refrigerator for 30 minutes, turning fish occasionally.

Preheat oven to 350 degrees F. Wrap tortillas tightly in foil. Heat in oven about 10 minutes or until heated through.

Preheat broiler. Drain fish; discard marinade. Pat fish dry. Place fish on the greased unheated rack of a broiler pan. Broil 4 inches from the heat for 5 minutes. Using a wide spatula, carefully turn the fish. Broil for 3 to 7 minutes more or just until fish flakes easily when tested with a fork. (Or place fish fillets in a well-greased wire grill basket. Grill on the rack of an uncovered grill directly over medium coals for 8 to 12 minutes or just until fish flakes easily when tested with a fork, turning once.)

With a fork, break broiled fish into 1/2-inch chunks. To assemble tacos, place lettuce in center of each warm tortilla. Divide fish chunks, sweet pepper, and red onion among tortillas. Fold tortillas in half over filling. If desired, serve with cilantro and/or mango slices. Makes 4 servings.