In large bowl, place rinsed and drained canned beans. With potato masher, mash beans until creamy but still a little chunky. Add remaining ingredients except for breadcrumbs, oil, lettuce, buns, and toppings.
Using your hands, work mixture together until fully blended. Shape mixture into 6 equal-sized patties about 1/2 inch thick. In medium bowl, place breadcrumbs. Press each burger into crumbs until lightly coated.
In frying pan, heat oil over medium heat. Add as many burgers to pan as you can, making sure not to crowd them. Cook for 3 to 4 minutes per side, being careful as you flip them. Remove and repeat with remaining burgers.
Serve burgers on lettuce leaves or on lettuce-lined toasted buns with toppings of choice.