Soak the beans overnight in a large heavy pot with enough water to cover the beans by 2 inches (5 cm).
1/2 lb dried pinto beans
The next day, cover and simmer the beans in the water they soaked in for 1 hour, until tender.
Add the tomatoes and simmer 5 minutes longer.
5 cups tomatoes
Meanwhile, in a very large heavy skillet, fry the bell peppers in the vegetable oil over moderate heat, stirring frequently, for about 5 minutes, or until limp.
3 medium green bell pepper, 1 tbsp vegetable oil
Add the onions and continue frying, stirring frequently, for 5 to 8 minutes, until the onions are "glassy".
4 medium onions
Add the garlic and parsley and set aside. In another large heavy skillet, melt the butter over moderate heat and brown the meats for 15 minutes, stirring frequently.