Grab a large canning jar that is just large enough to hold the lemons (a 32-ounce jar will hold about 7 to 10 Meyer lemons; if you want to halve this recipe, use a smaller jar). Cover the bottom of your canning jar with 1 to 2 tablespoons of kosher salt.Note: I like to use a canning jar with a rubber gasket to prevent the lid from corrosion.
Rinse the lemons and scrub them really well. Set aside 1 or 2 lemons for juicing at the end.
Cut off a thin slice from both ends of each lemon so they have a flat bottom. Stand the lemon up and slice lengthwise, almost all the way through but keep the lemon attached at the base. Flip the lemon by 90º and slice lengthwise again, as if quartering the lemons into wedges, but not all the way through.
Gently pry the lemons open but do not detach them. Fill each crevice with a generous amount of kosher salt (a generous tablespoon in my estimation). Seal the lemons up to close.
Add a few lemons to the jar. Press them down with a muddler, a pair of tongs, a pestle, or a sturdy spoon so that they release their juices and you can make room for more lemons. Pack the jar as tightly as you can with the salted lemons, pressing down to cover them with their juices. NOTE: If the juice released does not cover the lemons, squeeze the juice from the reserved 1 or 2 lemons on top. If covered by their juices and you have a little extra space, you can salt the remaining lemons and add them to the jar.
Cover the lemons with 2 tablespoons of kosher salt (and any optional flavorings). Seal the jar and let it sit at room temperature (I store it in my pantry) for at least 3 weeks, or until the lemon rinds are very soft. Gently shake the jar every day, turning upside down, for the first 2 weeks.
When ready to use, you can use the entire lemon, but it’s more common to scoop out the flesh and use only the peel. If desired, wash the lemon peel before using to make slightly less salty (I don't typically do this).