Score the pig skin, preferably with a Stanley knife so you can set the depth of the cut. Rub with pepper and salt. Pound garlic and rosemary using a mortar and pestle and rub into skin. Roast at 180C for about 2 hours. If the skin is not sufficiently crackled, remove and finish it under the grill. Serve with a mixed leaf salad (preferably soil-grown leaves such as radicchio, cos, rocket, sorrel or watercress) and a vinaigrette made with apple cider vinegar.