In a small bowl, whisk together the jelly, Worcestershire sauce and mustard. Set aside.
Heat a couple tablespoons of oil in a sauté pan over medium-high heat. Once the oil is hot, brown the pork on all sides, only about 30 seconds per side.
Place the chopped onions at the bottom of the slow cooker. Place the pork on top of the onions and pour in the juices from the pan. Season well with salt and pepper. Pour the sauce over top.
Cook the pork on high for about 5 hours, or until the pork easily falls apart.
When ready, remove the pork from the slow cooker and shred, removing the large bits of fat as you go. Return to the slow cooker and cook for an additional 30 minutes.
Serve the pork in hollowed out French bread buns with slaw.
