1. Heat oil in nonstick skillet over medium heat. Add onion, plum tomato, jalapeno, garlic and chili powder; sauté 5 minutes. Cool slightly.
2. Using fork, coarsely mash beans in bowl. Combine with onion mixture, breadcrumbs, 2 tablespoons of the barbecue sauce and egg white.
3. Shape mixture into four 1/2-inch-thick patties. (Can be prepared 4 hours ahead. Cover and chill.) It will look as though these little burgers will just fall apart and turn to mush, but they stay together really well once they "hit the pan"!
4. If grilling; oil the rack or spray grill rack with nonstick spray, then fire up coals to medium heat. If pan-frying, heat a little olive oil over medium heat.
5. Place patties on grill or in skillet and cook until golden brown and heated through, about three minutes per side.
6. Place burgers on buns. Serve with more barbecue sauce, and cheese, tomato, lettuce, avocado, or whatever topping you like!