1If fish steaks are large, cut into 6 serving pieces. Mix remaining ingredients except Tomato-Avocado Salsa in shallow glass or plastic dish. Add fish; turn to coat with marinade. Cover and refrigerate at least 30 minutes but no longer than 2 hours.
2Meanwhile, in medium bowl, mix all tomato-avocado salsa ingredients together. Set aside until ready to serve.
3Heat coals or gas grill for diirect heat. Remove fish from marinade; reserve marinade. Cover and grill fish 4 to 5 inches from medium heat 10 to 15 minutes, brushing 2 or 3 times with marinade and turning once, until fish flakes easily with fork. Discard any remaining marinade. Serve fish with salsa.