heat the oil in a 10-inch skillet over medium-high heat and brown the pork on all sides.  

mix the soup, ketchup, vinegar and brown sugar in a crock pot. add the pork and turn to coat.

cover and cook on LOW for 8 to 9 hours or until the pork is fork-tender.

take the pork from the cooker to a cutting board (plate or whatever) and let stand for 10 minutes.  shred the pork (i use 2 forks).

return the pork to the sauce (back to the cooker or put it all in another dish)

serve up the sandwiches.