Rinse beans carefully. (I use quick soak method). Add 16 cups water and bring to boil.
Remove from heat and cover for one hour.
Put beans back over fire and simmer slowly.
Saute onions, garlic, and peppers over medium heat in olive oil, about 10 to 15 minutes.
Add to beans.
Add tomatoes, paste, salt, sugar, chili powder, and cumin.
Simmer gently for 2 hours, or until beans are tender.
Serve with grated cheese, diced onions, and sour cream.
