First thing to do when preparing to cook a pork leg is to take it out of the fridge for an hour or so. What we want is the pork temperature to be raised towards room temperature and not at say 3-4 degrees. This helps the meat cook more evenly through the centre and stops the outer layer drying out towards the end of the cooking process.
Before cooking your leg have your butcher weigh the joint or weigh it yourself. You need to cook the joint in a preheated oven for roughly 25 minutes per 450 grams and then add on 30 minutes at 190 degrees C (gas mark 6). The rind on the pork should be well scored. The better the joint is scored the better crackling will be. By scoring the rind allows the heat to better transfer and penetrate the rind creating crispy rather than chewy crackling. If the butcher has not done this you can easily do it with a knife but preferably a Stanley knife. The most effective way of using a Stanley knife to score the rind is to push the end of the blade out to its smallest level, so you have in fact just the very end point of the blade to cut the meat. This ensures the knife penetration is consistent and not too deep. You are aiming to just penetrate into the fat layer and not to cut down into the fleshy meat.
When the cooking time has elapsed use your meat thermometer to measure the temperature of the joint. Ensure that the thermometer is inserted deep inside the middle of the joint. If you don’t do this you will skew the reading and may result in you failing to cook the joint perfectly. You will be looking for the temperature to read at least 63-64 degrees C. Once the meat has reached this temperature remove from the oven.