Method:
Preheat oven to 400°F. Heat oil in a large skillet over medium high heat. Add onions, salt and pepper and cook, stirring occasionally, until golden, 8 to 10 minutes. Add vegetables and cook until softened and hot throughout, whether you use raw, cooked or frozen veggies. Sprinkle 1/4 cup flour over vegetables, stir well and cook 2 minutes. Whisk in broth, bring to a boil and then reduce heat to medium low and simmer until thickened, 2 to 3 minutes. Stir in turkey, salt and pepper; transfer to a 9-x13-inch baking dish; set aside.
In a large bowl, gently combine 1 1/4 cups flour, sweet potatoes, baking soda, buttermilk, 1/2 teaspoon salt and 1/4 teaspoon pepper to make a thick batter. Do not over mix. Drop batter in large spoonfuls over turkey mixture to form 8 dumplings. Bake until dumplings are golden brown and cooked through, about 30 minutes.