Grilled Halibut

Cut fish into 4 equal pieces. For sauce: in medium saucepan, over medium heat, melt butter or margarine. Add mushrooms and cook, stirring frequently, until liquid evaporates, about 8 minutes. Add wine, nectarines and onions and cook until nectarines are slightly soft. Combine cornstarch and water; whisk into sauce, stirring constantly until slightly thickened. Set on side of barbecue to keep warm, if desired. Cook halibut in oiled barbecue basket on uncovered grill over medium direct heat 5 minutes on each side or until fish flakes easily with fork. Place on plates and spoon sauce over halibut; garnish with chives, if desired.