Seasoning: Season the pork with 1½ teaspoon of salt, 1 teaspoon of pepper, and paprika.
Cooking: Place the meat and onion in a small pot and pour in the vinegar and enough water to cover it.Cook covered over medium heat until the meat is very tender and flaky, adding more water during the process if it should need it to prevent it from burning (20-25 mins).Once the meat is cooked through let the liquid evaporate and brown the meat in the fat released (or add butter if there's not enough fat).Remove from the heat.
Shredding: Using two forks shred the pork as finely as possible. Set the meat aside.
Adding apples: Core and dice the apples and add to the still-warm meat.Mash the apples a bit with a potato masher, then let everything cool to room temperature.Between the heat from the meat, and the heat frying the empanadas later the apple will get a bit softer.
Serving: Keep covered until it's time to work on the empanadas, or refrigerate for up to 72 hours.
Video
Notes
Leftover pulled pork empanadas filling
If you have some leftover puerco asado, use it and skip to step 3.