Preheat broiler. In a large skillet cook turkey, green peppers, mushroom and onion over medium-high heat until turkey is no longer pink vegetables are tender, 8-10 minutes, breaking up turkey into crumbles; drain. Stir in 1/4 cup dressing and pepper., Spread remaining 1/4 cup dressing over cut side of bread. Place on a baking sheet. Broil 4-6 in. from heat until lightly toasted, 3-4 minutes. Spread turkey mixture over toasted sides of bread; top with cheese. Broil until cheese is melted, 1-2 minutes longer. Cut each half into 2 slices. Serve with additional sauce on the side.