PREHEAT oven to 350ºF. Cook and stir onions and red peppers in 1 Tbsp. margarine. Add to combined turkey, peas and carrots, sour cream, dressing, tarragon and black pepper; mix well. Spoon into 1-1/2-qt. casserole dish sprayed with cooking spray.
MELT 1 tsp. margarine in small skillet. Add Parmesan cheese and bread crumbs; cook and stir 3 min. or until lightly browned. Sprinkle over turkey mixture.
BAKE 30 min. or until heated through.