Preheat the oven to 230°C. Using a very sharp knife, score the belly fat. Pour a kettle full of boiling water over the fat side of the meat then pat dry. Rub the skin with the salt, sugar and chilli sauce. Place the pork, skin side down, on a rack set over a roasting dish. Half fill the roasting dish with boiling water, and place in the oven for 30 minutes. Turn meat so it’s skin side-up and roast for a further 30 minutes. Reduce the heat to 180°C and roast for another hour. Meanwhile, mix the pecan nuts with marmalade. Place the apples on a baking tray. Stuff the nuts into the cavity of each apple and squeeze over the lemon juice. Place in the oven and cook during the last 30 minutes of roasting time. For extra-crisp crackling, give the skin a final blast under the grill.