1In a large bowl, mash the cooked black beans with a fork or potato masher until mostly smooth.
Add the breadcrumbs, cumin, chili powder, salt, and diced red onion to the mashed beans. Mix until well combined.
Divide the mixture into four equal portions and shape each portion into a patty.
Heat a non-stick skillet over medium heat. Cook the patties for about 4-5 minutes on each side, or until they are browned and heated through.
Toast the whole wheat burger buns lightly in a toaster or on a skillet.
Place each patty on a toasted bun and top with a generous spoonful of tangy burger sauce.
Serve the veggie burgers warm and enjoy!