Heat gas or charcoal grill. Cut 4 (15x12-inch) sheets of foil. In medium bowl, mix pork, beans and barbecue sauce. Divide pork mixture evenly onto center of each sheet of foil. Sprinkle corn evenly over top. Place onion slice on top of each.
To form bundles, bring short sides of foil together; make several 1-inch folds. Fold open edges of foil to seal.
When grill is heated, place bundles on gas grill over medium heat or on charcoal grill over medium coals; cover grill. Cook 18 to 20 minutes or until pork is no longer pink in center. Carefully open bundles to allow steam to escape.