The process can be used with limes and grapefruits, too.
You only use the peel in dishes, you discard the flesh.
They are pickled just in their own juice, with a great deal of salt added. Some recipes add spice as well.
It is best to use a chunky or coarse salt. With fine salt, too much will be absorbed. And it is best to use uniodized salt, so that no discolouration happens and the lemons don’t take on a harsh flavour. It is best not to add water, as that can dilute the salinity which keeps it safe.
The fruit pieces must be covered at all times by the juice / salt slurry, or they will go mouldy. A weight to push them down can help.
When the pickled lemon pieces are ready to use, the flesh should fall off the peel easily.