Rinse shark with cold water; pat dry with paper towels. Set aside. Combine remaining ingredients except Salsa and avocado; pour over shark. Cover and marinate in refrigerator for 1 hour, turning once.
While shark is marinating, make Salsa.
Drain shark, reserving marinade. Place on well-greased grate 4-5 inches from hot coals. Cook 4-5 minutes; baste with marinade and turn. Cook an additional 4-5 minutes, or until shark flakes when tested with a fork. Top with avocado slices and Salsa. Makes 4-5 servings.