1In 8-inch square (2-quart) glass baking dish, place fish. In small bowl, mix brown sugar, salt, bourbon, mustard and onions; pour over fish. Cover; refrigerate 1 hour to marinate.
2Heat gas or charcoal grill. Remove fish from marinade; pour marinade into 1-quart saucepan and reserve. Carefully brush grill rack with canola oil. Place fish on grill. Cover grill; cook over medium heat 10 to 15 minutes, turning once, until fish flakes easily with fork and is slightly pink in center.
3Heat marinade to boiling; pour over fish.