Use large dry lima beans for this soup.
Soak beans overnight. (Drain or not, as you prefer.) Simmer in water to cover, 1-½ hours, covered. As beans cook, fry sausage in skillet. Remove meat with slotted spoon and set aside. Leave 1 tablespoon fat in pan. Saute celery in fat until tender. Sprinkle with flour and stir until blended. In separate pan boil potatoes in water to cover until tender. Drain. Slowly add ½ cup of hot bean liquid to flour mixture and stir until smooth. Add mixture to kettle along with potatoes and sausage. Heat thoroughly. Season with salt and pepper.