Heat oil in a large stock pot over medium heat. Add garlic, onion, and bell pepper. Saute for 5 minutes, stirring to avoid sticking. Add cumin and cook for another 30 seconds.
Stir in water and chopped chili peppers. Drain beans and add to pot along with remaining ingredients. Stir and bring to a boil. Reduce heat to low and simmer for 5 minutes. Remove 1 cup of mixture and mash the beans. Return to pot and cook an additional 5 minutes.
Serve with mango on the side. (Serving size: 1 cup chili, 1/2 cup mango)