For a vegetarian option, omit the sausage and use olive oil instead of bacon drippings. Consider adding a pinch of red pepper flakes for extra heat. If you don't have leftover mashed potatoes, you can make a fresh batch using your favorite recipe. Just be sure to let them cool slightly before adding them to the soup. The soup can be stored in the refrigerator for up to 3 days. Reheat gently over medium heat, stirring occasionally.