How to Make It
Place beans in a large bowl; mash with a fork. Place 1 toasted bun, torn, in a food processor; pulse until fine crumbs form. Stir breadcrumbs, cumin, and next 5 ingredients (through egg white) into beans.
Divide and shape bean mixture into 4 (1-inch-thick) patties. Heat oil in a large skillet over medium-high. Add patties to pan; cook 4 minutes on each side or until browned.
Divide cheese evenly among patties; cook 1 minute or until cheese melts. Top bottom halves of remaining 4 buns evenly with patties, pico de gallo, lettuce, and top halves of buns.