Cut the pork belly, rind on, into chunks about 4–5 cm across.
Put the pieces in a large pan and add enough water to cover them, along with a good pinch of salt.
Bring to the boil over medium–high heat. Once boiling, reduce to a simmer and cook for 45–60 minutes.
When the water has completely evaporated and only the fat remains in the pan, turn the heat up to medium.
Fry the pork pieces in their own fat, stirring occasionally so they brown evenly, for 30–40 minutes.
Remove the cracklings with a slotted spoon and drain on kitchen paper to soak up any excess fat.
Serve the cracklings hot with a squeeze of lemon, if you like.