In a food processor, combine black beans, red onion, garlic, cilantro, sriracha, mayonnaise, cumin, soy sauce, and black pepper. Pulse until mixed but still chunky.
Transfer mixture to a bowl, add the egg and breadcrumbs, and stir until combined. Let sit for 5 minutes.
Divide the mixture into six portions and shape each into a 3 1/2-inch diameter, ½-inch thick patty.
Heat 1 tablespoon of oil in a skillet over medium heat. Cook the patties for 4-5 minutes on each side until browned and heated through. Repeat with remaining oil and patties.
Serve the patties on buns with your choice of toppings.