Clean the fatback and cut it into pieces of your choice.
Put the water and coarse salt in a deep container on the stove. Leave it to heat until the water itself comes to a boil.
Once boiling, place each piece of fatback in the water. Leave it for about 2-3 min. with the skin side facing the water, then flip over. Do this for all of the pieces.
Leave them aside to cool - both the brine and the fatback. Strain the brine through a gauze.
Arrange the fatback pieces in a 12 1/2 cups (3 L) jar and pour on the strained brine.
It'll be ready for consumption after 1 week at the most.