from Moroccan Modern by Hassan M'souli
(my comments italicized)
1 1/2 cup rock salt (I've also seen kosher salt recommended for preserving lemons)
4 1/4 cups filtered/purified water, boiling
juice from 1 lemon
8 Cardamom pods
2 small red chiles (not mexican)
2 bay leaves
olive oil to cover
Clean lemons and soak in filtered water for 3 days. Change water daily.
Cut pockets in each lemon, from 1/4 inch from top to 1/4 inch from bottom. Fill pockets with salt. Layer tightly in a sterilized jar.
Cover with boling water, lemon juice, remaining salt, cardamom, chilies and bay leaves. Top with a thin layer of olive oil. Seal tightly, let sit in refirdgerator for one month before using. Good for one year, refrigerate.
*I bet you could put this in a boiling bath to seal the jar, and not refrigerate it. Then, it would probably last on the shelf for over a year, but of course you'd have to refrigerate it when it is opened.
painting by Julian Merrow-Smith, from his daily Postcard from Provence.