1. Combine first 6 ingredients in a small bowl. Reserve 1/4 cup mixture. Place remaining mixture in a large heavy-duty zip-top plastic bag; add fish. Seal and marinate in refrigerator at least 30 minutes, turning once.
2. Prepare grill.
3. Remove fish from marinade, discarding marinade.
4. Place fish on grill rack coated with cooking spray; grill 3 minutes on each side or until fish is medium-rare or desired degree of doneness. Transfer fish to serving plates; spoon reserved soy sauce mixture over fish and top with cilantro.