The day before:
Cut the pork belly into 1″ (2.5 cm) x 3″ (7.5 cm) pieces.
Place them on your cutting board, making sure they are all flat.
Season with fine salt and pepper generously.
Turn the pieces over and season again.
Place the pieces in a large dish, cover with plastic wrap, and refrigerate for at least 24 hours.

The next day:
Chop the back fat into small pieces. Reserve.
In a large cauldron, bring the water to a boil and add the back fat to melt it.
Cover the cauldron and let it melt, leaving a small broth. Stir often with a wooden spoon.
The operation can take more than an hour.
If you have lard, simply melt it.

Remove some of the melted fat and heat it in a pan.
Sear the pork belly pieces on both sides until they have a nice golden color.

As soon as the pieces are colored, transfer them to your cauldron of melted fat. It is essential that all the pieces are covered with fat.
Bring to a boil, reduce the heat, leaving a small broth, cover, and let cook for 2 hours.
Stir occasionally with a wooden spoon, so that some pieces do not stick to the bottom.

Let it cool in the cauldron for 1 hour, then drain it in a strainer placed over a plate.
Let it cool completely.
Enjoy with Dijon mustard, bread, and green salad!