Place fish in a shallow baking dish. Combine soy sauce, garlic, lemon juice, and sugar; pour over fish. Cover and marinate in refrigerator for 30 minutes.
Remove fish from marinade; discard marinade. Sprinkle fish evenly with peppercorns, pressing firmly so pepper adheres to fish.
Place fish on rack of a broiler pan coated with cooking spray. Broil 51/2 inches from heat (with electric oven door partially opened) for 8 to 10 minutes or until fish flakes easily when tested with a fork.