Heat oil in skillet set over medium-high heat; cook black beans, BBQ sauce, cumin and chili powder for about 5 minutes or until beans are heated through and well coated. Remove from heat and let cool slightly.
Meanwhile, spread guacamole, if using, evenly down along center of each tortilla, leaving 1-inch border at top and bottom. Top with lettuce, black bean mixture, tomatoes, red onion, cilantro and green onions. Fold up bottom of tortilla over filling, then fold in sides; roll up tightly starting from the bottom.