Garnish: chopped cilantro, you can also top with avocado slices, cheese or low-fat sour cream. If you like it spicy add chopped jalapenos.
Sautee onions in the olive oil in a large pot over medium heat on the stove, until caramelized, about 10 minutes. Add garlic and chipotle chilies. Add ground buffalo and cook until meat is cooked through, about 5-8 minutes. Add beef stock, beer, beans and tomatoes. Cook until comes to a boil, lower heat to simmer and cook for about 30 minute.