Prepare the day before, refrigerate overnight, and rest after cooking for 15 mins.
For 30 years, I have tried to perfect the crunchiest, tastiest crackling and succulent roast pork. Having tried all the methods out there, this is the one that works for me.
Pork joint with skin
Thorougly defrost the joint the day before cooking. You can use a supermarket joint, which contrary to some opinions, works just perfectly. Make sure you unwrap it to defrost it, to discourage it from becoming too moist.
If the skin has not been scored, do so with a sharp Stanley Knife in long strokes about 1cm or less apart all over the skin.
Pour boiling water from a kettle all over the joint as it sits skin side up. This will cause the skin to contract and go pale. Once done, dry immediately with kitchen paper.
Rub salt into the skin thoroughly, then wrap in a clean dry tea towell and put into the fridge overnight.
In the morning, unwrap the meat (remember to put the tea towell directly into the wash) and rub the skin with a small amount of butter all over.
Put the joint into a low oven at 160 deg C for 3 hours. I find this just right for a larger joint of around 2kg, however if you want to check if your meat is ready with a meat thermometer, the internal temperature should be 60-70 deg C.
Take the joint out to rest, and immediately separate the crackling from the meat in one piece and put it onto a small baking tray. Tap the crackling with a fork, if it sounds like its not entirely crisp (and it usually isn't at this stage) pop the tray back into the oven and turn the temperature up to 200-220 deg C for 10-20 minutes until crisp.
Use a sharp knife to cut the crackling into strips for serving. Lovely served as a traditional English roast with roast potatoes, baked apple wedges and vegetables.