Place black beans, bread crumbs, egg, onion, garlic, salt, pepper and cumin in a food processor; pulse until the mixture has almost become a paste, with some lumps remaining. Form mixture into 6 patties.
Heat oil in a cast-iron skillet to medium heat. Place patties in skillet; cook until lightly browned on the edges, 3-4 minutes per side. Serve on buns with desired toppings.