Prep the pork belly skin. Pat the pork belly very dry with paper towels.
Use a sharp knife to lightly score the skin in a crosshatch pattern, making shallow cuts that do not pierce the meat. Alternatively, prick the skin all over with a skewer or meat tenderizer, avoiding the flesh.
Dry-brine for crispness. In a small bowl, mix baking powder and 1 teaspoon of the salt. Rub this blend only onto the skin.
Flip the pork and season the meat side with the remaining salt, black pepper, garlic powder, onion powder, and five-spice. Place the pork belly uncovered on a rack set over a tray and refrigerate for at least 6 hours, preferably overnight. This dries the skin and boosts flavor.
Bring to room temp. Take the pork belly out of the fridge 30–40 minutes before cooking.
Pat the skin dry again if any moisture appears. Brush the skin lightly with vinegar, then rub a thin layer of oil over the skin.
Preheat the air fryer. Set your air fryer to 360°F (182°C) for 5 minutes to preheat. This helps the skin start crisping right away.
Create a drip shield (optional but helpful). Line the bottom drawer of the air fryer with a bit of foil for easy cleanup, leaving airflow vents clear.
Do not cover the basket surface where the pork sits.
Cook low to render fat. Place the pork belly skin-side up in the basket. Air fry at 360°F (182°C) for 35–40 minutes, or until the fat has clearly rendered and the edges begin to blister. Check halfway and dab any visible moisture on the skin with a paper towel, if needed.
Blast to crisp the skin. Increase the temperature to 400°F (204°C) and cook for another 12–18 minutes, until the skin is deeply golden and puffed with crackling bubbles.
Rotate the basket once during this stage for even browning.
Rest before slicing. Transfer the pork belly to a cutting board and rest for 10–15 minutes. This keeps the juices in the meat and preserves the crisp skin.
Slice the right way. Use a serrated knife to gently saw through the crackling. Slice into bite-size pieces or thick slabs.
Serve with lime, chili crisp, or a soy-vinegar dip.