In a large bowl, combine the first eight ingredients. Crumble turkey over mixture and mix well. Shape into four patties.
In a large nonstick skillet coated with cooking spray, cook patties over medium heat for 6-8 minutes on each side or until a meat thermometer reads 165� and juices run clear.
Serve on buns with lettuce, tomato and onion. Combine sour cream and dressing mix; spoon over burgers. Yield: 4 servings.