Preheat oven to 180°C (350°F).Using a small sharp knife, score the pork skin at 1 cm intervals.Pat the skin dry with paper towel. Rub the salt and oil into the skin and incisions.Place the pork, skin-side down, on an oven tray and roast for 1 hour 30 minutes.Remove the pork from the oven and increase the oven temperature to 220°C (425°F).Working quickly, arrange the onion and lemon on the oven tray next to the pork. Turn the pork over onto the onion and lemon. Roast for a further 20–30 minutes or until the skin is golden and crispy and the meat is tender.  NoteFor the crunchiest pork crackling, be sure to thoroughly dry the skin. If you have the time, you can refrigerate the pork, uncovered, for 2 hours or overnight. This will let the skin dry out even further, before you oil and salt the rind.This recipe is from  on SBS Food (Channel 33). Stream episodes via .