1. Rinse fish and pat dry.
2. Place on a grill over a solid bed of hot coals or on a gas grill set at high heat (you can hold your hand at grill level only 2 to 3 seconds); close lid on gas grill. Cook, turning once, until fish is opaque but still moist-looking in thickest part (cut to test), 12 to 14 minutes. Transfer fish to a platter. Season to taste with salt and pepper.
3. To assemble each taco, stack 2 tortillas; add chunks of fish, relish, and sour cream. Squeeze lime over filling, fold tortillas, and eat.
*Check fish for bones before cooking. Press surface with your fingers to locate; pull out with tweezers.
Nutritional analysis per average taco.