Pat the pork belly skin completely dry with paper towels — this is essential for crackling. Use firm pressure and repeat with fresh towels until no moisture remains.

Using a very sharp knife, score the skin in a crosshatch pattern: make cuts about 5mm apart and 2–3mm deep, angling the blade at 45 degrees. Score across the grain in both directions to create diamond shapes. Do not cut into the flesh.

In a small bowl, mix the apple cider vinegar, sea salt, caster sugar and black pepper until the salt begins to dissolve.

Rub the vinegar-salt mixture evenly over the scored skin, working it into the cuts. Let the pork sit uncovered at room temperature for 10 minutes to allow the skin to dry slightly.

Preheat your air fryer to 200°C for 5 minutes.

Place the pork belly skin-side up in the air fryer basket. If it doesn't fit flat, fold it slightly or cut into 2 pieces — the skin should face upward.

Air fry at 200°C for 35–40 minutes. Check at 30 minutes: the skin should be blistering and beginning to crackle. If it's not, continue cooking. The skin will darken significantly (almost charred in places) — this is correct.

Insert a meat thermometer into the thickest part of the meat (not touching skin): aim for 62–64°C internal temperature. The crackling should sound crispy when tapped gently.

Transfer the pork belly to a warm plate and rest, uncovered, for 10 minutes. This allows carryover cooking to finish the meat to medium (65–68°C) whilst the crackling sets.

Slice between the score marks using a sharp knife, wiping the blade between cuts to avoid ragged edges.

Serve immediately with lemon wedges and fresh thyme, with any pan drippings spooned over the top.