Lay out a large piece of heavy duty foil. Pour 1 cup barbecue sauce over foil. Sprinkle with dried onion flakes. Place roast over barbecue sauce on foil. Top roast with another cup of barbecue sauce and more minced onion. Add carrots and sliced potatoes if desired. Close foil package and seal well. Cook over fire on grill, turning every 20 minutes for about 2 hours.
