Wash and drain pinto beans; place in stockpot, cover with water and let soak overnight. The next day, bring water to boil, lower heat and simmer 1 1/2 to 3 hours, or until beans are tender, drain. (if you use canned beans, omit these two steps).
Melt butter in large skillet. Add onions chilis and garlic. Saute until onions are soft. Add chopped sirloin and cook over moderate heat until meat is brown.
In seperate pan, brown sausage and pour off fat. Add sausage to meat mixture. Sprinkle with flour and stir to blend, then transfer to Dutch oven or 8-quart kettle. Add pinto and baked beans and all remaining ingredients, except sour cream; bring just to a boil.
Lower heat and simmer about 30 minutes. Skim off fat with a cold spoon as it rises to the tp. Serve with sour cream.