Preheat the air fryer to 400°F.*
In a large bowl, combine the oil, salt, and pepper.
Add the pork belly pieces to the oil mixture, covering each piece.
Lay the pork belly pieces in a single layer in the basket of your air fryer. (Depending on the size of your air fryer, you may have to work in batches.)
Air fry the pork belly cubes for 18-20 minutes, shaking and flipping them a couple of times throughout the cooking time. Please note: Air frying times will depend on the size of your pork belly pieces and the size of your air fryer.
When done cooking, place the pork belly bites into a large bowl. Set aside as you prepare the maple mustard sauce.
In a small bowl, mix together the maple syrup, mustard, and vinegar. Reserve about 3 tablespoons for dipping.
Pour the maple mustard sauce over the cooked pork belly bites, tossing to coat.
Serve warm with the reserved sauce for dipping.