Combine ready sauce with the cider vinegar, garlic, ginger, soy, and water in a slow cooker (if using).
Add sliced onion and pork. Ensure the pork is coated with the sauce.
Cook 4 hours on high or 8 hours on low.
When ready, remove from cooker and pull the pork apart with a fork. Remove onions and 2-3 tbsp of sauce from the slow cooker, mix with the pulled pork.
Serve in sliders, buns, taco shells, lettuce cups or in wraps with salad. Serve cold in sandwiches or rolls the next day.