Finely dice the bell pepper and onion
Mash the beans in the bowl; you may optionally reserve some from being mashed if you like whole beans in your patties
Mix in peppers, onions, garlic, chili powder, cumin, and egg
Mix in a half-cup of bread crumbs, until you have a dry, grainy paste. If mixture is still wet, mix in small amounts of bread crumbs until it's dry.
Divide into quarters (or fifths/sixths if you prefer smaller/tiny patties)
Fry in a little oil over medium heat until each side is slightly browned