If you want to get delicious belly pork, with crisp crackling, here's a good way. You'll need a deep roasting tin, an onion or two, some garlic, some decent stock and, of course, a belly pork joint. If it comes rolled, undo the string and flatten it out, you want a flat crackling surface.
First thing is to scald the crackling by pouring boiling water over the skin and patting it dry before scoring it. I use a very sharp modelling knife for this. If you want. you can use a skewer and poke some holes through the skin and into the layer of fat under the skin and push slivers of garlic into the fat. This works rather well. Rub the skin with decent oil and season with sea salt.
Slice the onions finely and cover the base of the roasting tin with them, adding the garlic either sliced or crushed (your call) before just covering with the stock. Put the pork on top, using onions as a trivet to present the flattest possible skin surface.
Give it 30 minutes in the hottest oven you can manage before turning right down to Gas Mark 3 or even 2 and giving it another 2-3 hours (more if you like) before removing from the tin to rest.
Decant the stock, onions, garlic and all the fantastic juices from the pork into a small saucepan, using a scraper to get all the sticky bits off the tin, then whizz up with a stick blender to produce the gravy. Blend until pretty much smooth, if you're a nonce or a homosexual, feel free to sieve the gravy to make it absolutely smooth, but bear in mind that real men will spurn you.