Method

Toast the fennel seeds and peppercorns in a dry frying pan for a couple of minutes. Pound them together in a pestle and mortar with some flaked sea salt, the thyme and garlic to make a paste. Mix with 2 tbsp olive oil and rub all over the flesh of the pork. Cover and chill, leaving to marinate for a few hours or overnight.
When ready to cook, rub the skin of the joint with plenty of salt and 1 tbsp more olive oil.
Sit on a wire rack in a roasting tin and roast at 180C fan for 30 mins. After this time, squeeze the lemons over the skin and turn the heat down to 160C fan.
Roast for a further 2 hrs.
Finally, turn the heat back up to 200C fan and give it a final blast for another 30 mins or so, to finish the crackling.
Allow to rest somewhere warm for 20 mins. Carve up into chunks or slices