Preheat oven to 350 degrees F (175 degrees C), and grease a 9x12 inch baking dish.
Mix the ground turkey, bread crumbs, onion, egg, salt, and pepper in a bowl, and form into 6 patties. Place the patties in the prepared baking dish.
Stir together the maple syrup, ketchup, mustard, vinegar, and oil in a bowl, and set aside.
Bake the patties in the preheated oven for 20 minutes, remove from oven, and turn them over.
Drizzle the patties with the maple syrup mixture, return to the oven, and bake until the patties are browned and the sauce is bubbling and thickened, about 45 minutes.
