Scrub lemons. Cut 1 end off each lemon. Hold a lemon cut side up and slice lengthwise down the center, stopping before the knife cuts all the way through the fruit. Rotate lemon a quarter-turn and slice again lengthwise down the center, stopping before the knife cuts all the way through the fruit. Repeat with remaining lemons. (Lemons will be quartered, but still attached at 1 end.)

Pour salt into a medium bowl. Working in batches, add cut lemons, a few at a time, and rub the flesh of each lemon with salt. Add a few tablespoons of salt from the bowl to the bottom of a sterilized ½-gallon glass jar. Push the first few lemons against the bottom of the jar. They will release juice. Add a few tablespoons of salt from the bowl to the jar, along with a sprinkle of herbs and spices, if using. Salt a few more lemons in the bowl and transfer to the jar, repeating the process until the jar is full. You want to use all the salt in the bowl, so be generous as you layer the lemons and dump any leftover salt from the bowl into the jar at the end.

Press lemons down with a wooden spoon to release more juice. Pour additional lemon juice into the jar to fill all space around the lemons. Cover jar with a sterilized lid and shake well.

Let lemons ferment at room temperature, giving the jar a gentle shake or turn every day or so. Lemons will be ready to eat in 3 weeks, at which point you can transfer jar to the refrigerator where they’ll keep for up to 1 year.