Rinse pork roast.
Make sure rind is scored well. (You can ask your butcher to do this.)
Pour boiling water over, pat dry. (This process should lift the rind off the meat and help it to crisp.)
Rub oil, vinegar and salt to taste into the rind and scoring. Repeat at least twice.
Place the roast into the dish you plan on cooking it in and leave uncovered in the fridge for up to 2 hours if possible.
Preheat fan forced oven to 150°C and set a rack on the lowest rung of the oven.
When ready to roast, pour enough liquid stock around the pork, carefully avoiding pouring any liquid onto the skin, to just reach the fat line of the meat. Add some white wine to this liquid if you wish, again not coming up past the fat line. The amount of these ingredients you need will vary and depend on the size of the roast as well as the size of the pan you roast it in. (Closer fitting pan is better.)
Place into the oven on the bottom rack and cook for approximately 90 minutes, but do keep an eye on it, topping up liquid occasionally as needed.
Change the oven setting to a grill function on 200°C, leaving the roast on the bottom rack. Watch it carefully. It can go from perfect to black in a matter of minutes. When you are happy with the look of the crackling, remove and rest as instructed before serving hot with accompanying dishes.