We seek out thick skinned lemons from non-GMO, chemical fertiliser free, pesticide free, growers that don't wax or place little stickers on each individual lemon.  Whilst this is not a lemon desirable for most, most aren't using the the skins for preserving.  This is a simple product; lemons, salt and nothing more but a whole lot of waiting time (two months minimum) in a cool, dark, cellar.  Use as a condiment, or ingredient in a myriad of Indian or North African dishes.