Heat the oil in a 10-inch skillet over medium-high heat. Add the pork and cook until well browned on all sides.
Stir the soup, ketchup, vinegar and brown sugar in a 5-quart slow cooker. Add the pork and turn to coat.
Cover and cook on LOW for 8 to 9 hours* or until the pork is fork-tender.
Remove the pork from the cooker to a cutting board and let stand for 10 minutes. Using 2 forks, shred the pork. Return the pork to the cooker.
Spoon the pork and sauce mixture on the rolls. *Or on HIGH for 4 to 5 hours.