Turn the pork belly over so that the skin is facing up again. If you have sliced the pork belly in half, re-arrange it so that it is in the original formation.
Place the pork belly onto a large sheet of foil.
Fold up the sides of the foil so that it forms a "box" around the pork belly, with the sides just slightly higher than the meat.
Brush the skin with some vinegar.
Generously sprinkle an even layer of salt all over the skin.
Allow the pork belly to rest for about 5 minutes.
Place a paper liner in the air fryer under the basket (optional).
Carefully place the pork belly into the air fryer basket.
Bake the pork belly at 120°C/248°F for 30 minutes. If you are using a regular oven, bake at 120°C/248°F with fan.
After 30 minutes, the salt should have hardened into a thick crust. If there still remains a lot of grains of salt on the skin, continue baking at 5 minute intervals.
You should be able to remove the salt crust in one large piece, or several large pieces.
Use some kitchen paper to brush off any excess salt from the skin, as well as the sides of the meat.
Remove and discard the foil lining.