The distinctive texture and flavor of preserved lemons is essential to not only traditional Moroccan cooking, but also to the contemporary cooking of some of the best chefs in the South of France, Spain, England, and the USA.
As Paula Wolfert - the world famous author of many cookbooks on Mediterranean cuisines - notes, "their unique pickled taste and special silken texture cannot be duplicated with fresh lemon or lime juice, despite what some food writers have said."
Quarter the lemons from the top to within 1/2 inch of the bottom, sprinkle salt on the exposed flesh, then reshape the fruit.
Place 1 tablespoon salt on the bottom of the mason jar. Pack in the lemons and push them down, adding more salt, and the optional spices between layers. Press the lemons down to release their juices and to make room for the remaining lemons. (If the juice released from the squashed fruit does not cover them, add freshly squeezed lemon juice — not chemically produced lemon juice and not water.*) Leave some air space before sealing the jar.
Let the lemons ripen in a warm place, shaking the jar each day to distribute the salt and juice. Let ripen for 30 days. To use, rinse the lemons, as needed, under running water, removing and discarding the pulp, if desired — and there is no need to refrigerate after opening. Preserved lemons will keep up to a year, and the pickling juice can be used two or three times over the course of a year.
I first learned to make preserved lemons from directions in Paula Wolfert's book Couscous and Other Good Food From Morocco.
Preserved lemons, sold loose in the souks, are one of the indispensable ingredients of Moroccan cooking, used in fragrant lamb and vegetable tagines, recipes for chicken with lemons and olives, and salads. Their unique pickled taste and special silken texture cannot be duplicated with fresh lemon or lime juice, despite what some food writers have said. In Morocco they are made with a mixture of fragrant-skinned doqq and tart boussera lemons, but I have had excellent luck with American lemons from Florida and California.
Moroccan Jews have a slightly different procedure for pickling, which involves the use of olive oil, but this recipe, which includes optional herbs (in the manner of Safi), will produce a true Moroccan preserved-lemon taste.
The important thing in preserving lemons is to be certain they are completely covered with salted lemon juice. With my recipe you can use the lemon juice over and over again. (As a matter of fact, I keep a jar of used pickling juice in the kitchen, and when I make Bloody Marys or salad dressings and have half a lemon left over, I toss it into the jar and let it marinate with the rest.) Use wooden utensils to remove the lemons as needed.
Sometimes you will see a sort of lacy, white substance clinging to preserved lemons in their jar; it is perfectly harmless, but should be rinsed off for aesthetic reasons just before the lemons are used. Preserved lemons are rinsed, in any case, to rid them of their salty taste. Cook with both pulps and rinds, if desired. excerpt from Paula Wolfert