Cut the pork belly with skin into pieces about 1 1/2 to 2 inches each.
Place the pieces in a large pot, add enough water to cover, and season with a pinch of salt.
Bring to a boil over medium-high heat. Once boiling, reduce heat to low and simmer for 45 to 60 minutes, or until all the water has evaporated and only the rendered fat remains.
Increase the heat to medium.
Fry the cracklings in their own fat, stirring occasionally, until golden brown and crispy, about 30 to 40 minutes.
Using a slotted spoon, transfer the cracklings to a plate lined with paper towels to drain any excess fat.
Serve the cracklings hot with a squeeze of lemon juice, if desired.