Heat butter and oil in large pot on medium heat. Add one onion (about 2 cups) and 3 diced garlic cloves and saute until soft. In a separate frying pan, cook beef until browned. Drain fat and add beef to the large pot along with the remaining ingredients except the black beans. Simmer uncovered for at least one hour. Add beans before serving.Garnish with sour cream, minced green onions, grated cheddar cheese, minced red pepper.