Meanwhile, heat dressing in large nonstick skillet over medium heat. Add onions, garlic and thyme; cook, stirring frequently, 3 min. or until onions are crisp-tender. Add gravy, ketchup and Worcestershire sauce; mix well. Bring just to boil, stirring occasionally. Add turkey and mixed vegetables; stir. Cook and stir 5 min. Soon into 2-L casserole dish sprayed with cooking spray.