HEAT grill to medium heat.
GRILL steaks 7 to 8 min. on each side or to medium doneness (160ºF).
MEANWHILE, cook bacon in large skillet until crisp. Remove bacon from skilllet; drain on paper towels. Discard drippings from skillet. Add mushrooms to skillet; cook 5 min., stirring occasionally. Stir in bacon, steak sauce, sherry and sugar. Bring to boil; simmer on medium-low heat 5 min., stirring occasionally.
SERVE steaks topped with mushroom sauce.