About 6 lemons for preserving
About 6 more lemons for juicing, or enough to make ½ to 1 cup lemon juice
About ¾ cup kosher salt
Scrub the 6 lemons you will be preserving with a vegetable brush under cold running water. Dry them very thoroughly.
Pour salt into large bowl. Stand lemon stem end down on cutting board and use knife to cut down into it as though you were going to cut it in half, stopping ½ inch above stem. Make a perpendicular cut, again stopping short of the stem, so the lemon is quartered but still intact.
Holding the lemon over the bowl, spread the four quarters open and pack in as much salt as you can, allowing the excess to fall back into the bowl, up to 2 tablespoons per lemon.
Put the lemon cut-side up in a standard 4-cup mason jar and repeat with as many lemons as the jar will hold, pushing them down hard so they squeeze in tightly. Note: the amount of lemons you’ll be able to fit depends on the size of your lemons. If you can’t quite fit the last lemon into the jar, put the lid on the jar and leave it on the counter overnight. You can add the last lemon the next day, when the lemons are softer.
Pour juice into the jar until it is filled to the brim and the salted lemons are completely submerged.
Put the lid on the jar, running it until it’s just finger-tight (over-tightening can keep air from escaping and cause the lid to buckle). Note: put the jar in a dark spot, like a cupboard or pantry, not in the refrigerator. For the next week, turn and shake the jar once a day to redistribute the salt that has settled to the bottom. Add more lemon juice if you notice that the lemons are no longer submerged.
Let the jar sit in that dark cupboard for a month. If you notice a little bubbling around the edge of the jar lid, don’t worry. That’s a normal part of the fermentation process.