Wash a wide-mouth one (1) pint glass canning jar (with screw lid or air-lock lid) in very hot, soapy water. Rinse well with hot water. Dry and turn upside down on a clean cloth. NOTE: You can use any size jar you desire - just alter the amount of lemons, salt, and lemon juice accordingly.
Scrub lemons with a vegetable brush under warm water; rinse well and dry with a clean cloth. Cut lemons lengthwise into quarters and place into a large bowl. Add the salt and toss, using a spatula to cover the lemon quarters with salt.
With clean hands or tongs, place the lemon quarters into the jar, compacting them down as best as you can (this makes room for all the lemon quarters and helps to release their juices). When the jar is 1/2 full, put some salt on top of the lemons and place the remaining lemons into the jar. Using the spatula, scrape the rest of the salt from the bowl into the jar over the lemons.
Pour just enough freshly-squeezed lemon juice into the jar to completely cover the lemons. Wipe the rim clean with a damp clean cloth; seal the lid on tightly.
Place the jar in a cool, dark place for at least three (3) weeks (longer if needed). To distribute the juice and salt, every 3 to 4 days, turn the jar over (on end), let sit for a few hours, then turn the jar upright. The lemons are ready for use when the rinds become soft and come away from the flesh and pith very easily.
To use the preserved lemons, pull the lemon quarter out of the jar, as needed, using tongs to avoid contaminating the inside of the jar with bacteria. Rinse the lemon quarter under cool water and remove the lemon pulp and seeds. Use only the pickled lemon peel. There is nothing wrong with using the lemon pulp, but pickled lemons are a powerful ingredient and must be used sparingly. They are actually very refreshing.
After the jar has been opened, store the remaining preserved lemons in the refrigerator for up to 1 year.
Variation: If desired, you can add spices to the lemons for preserving (cloves, coriander seeds, peppercorns, cinnamon stick, bay leaf, etc.).
Makes 1 pint jar.