Pulse black beans in a food processor until roughly chopped. Alternately, you can mash in a bowl with a fork.
Add red pepper, onions, and garlic to beans and pulse all together in the food processor until a "paste" is made.
Add black bean mixture to a large bowl along with egg, seasonings, and stuffing. Mix together really well, preferably with your hands, so it all becomes incorporated.
Using 1/3 of a cup, divide mixture into patties and fry them up in a frying pan or non-stick griddle on medium heat until brown on one side, about 5-8 minutes. Flip and brown the other side.
Once browned, you can create your burger. Top a hamburger bun with stuffing patty, mashed potatoes, green beans, and gravy. Either top with bun or eat open-faced.