Make a large incision in the fatty part of the pork belly to help the fat render properly. Sprinkle with salt and let it rest for 20 minutes.
In a deep wok or pot, submerge the pork belly in water and boil over medium heat for 15 minutes.
Once boiled, take the pork belly out and continuously prick the skin with a fork; this helps render the fat and leads to a crisper finish.
Place the pork belly skin-side down in a dish and cover the skin with a very thin layer of vinegar for 20 minutes. After 20 minutes, pat the meat dry using paper towels.
Heat oil in a wok or skillet, then carefully add the pork belly. Cover and fry each side for 5 minutes over medium heat, watching for splatters.
Let the pork belly cool, then fry skin-side down over high heat for 2 minutes with a lid on to achieve a crispy skin.
Allow the meat to rest for a few minutes after frying to let the juices settle, then slice and serve.