preheat oven to 325°. In a large bowl stir together Brown sugar, ketchup, salsa, barbecue sauce, mustard and steak seasoning. Stir in pork and beans, butter beans, kidney beans and onion. Transfer the mixture to a lightly greased 2 1/2 to 3 quart casserole.
Cover and bake for one hour. Uncover beans and stir. bake, uncovered, about 45 minutes more or until desired consistency, stirring occasionally. Beans will thickened slightly as they cool. If desired, top with broken potato chips. Makes 10 to 12 servings.