Thaw fish, if frozen. Rinse fish; pat dry with paper towels. In a small bowl stir together lemon peel, lemon juice, pepper, and garlic.
Preheat broiler. Place fish on the greased unheated rack of a broiler pan. Brush with half of the lemon juice mixture. Broil 4 inches from the heat for 5 minutes. Using a wide spatula, carefully turn fish. Brush with the remaining lemon juice mixture. Broil for 3 to 7 minutes more or until fish flakes easily when tested with a fork.
Cut the fish into 2 portions. Sprinkle with green onion and serve with orange slices. Makes 2 servings.