Cover pinto beans with water in a bowl and allow to soak overnight.
Drain.
Melt butter in a 6-quart stock pot over medium heat. Cook and stir onion and celery in butter until vegetables are tender, about 5 minutes.
Stir garlic into onion mixture until fragrant, about 1 minute more.
Stir beef broth, tomato juice, sugar, and drained pinto beans into the vegetable mixture and bring to a boil; reduce heat to medium-low and simmer until beans are tender, about 1 hour and 15 minutes.
Mix potatoes, carrots, oregano, salt, and black pepper into the bean soup; simmer until potatoes are tender, about 30 minutes more.
Preheat the oven's broiler and set the oven rack about 6 inches from the heat source.
Place smoked sausage on a baking sheet.
Bake sausage in the preheated oven until browned, about 10 minutes.
Cut sausage into quarters, then slice.
Add sausage and parsley to the soup; continue to simmer for 10 more minutes.