Scrub the lemons. Cut 4 of them into quarters and remove any seeds. Pour the salt into the bottom of a pint mason jar. Add the quartered lemons and bay leaf, if desired, to the jar, pushing them down to squeeze the lemons in. Juice the remaining lemon and add the juice to the jar to completely cover the cut lemons. Make sure there’s no air space in the jar, then seal it with the lid. Store in the refrigerator for 3 to 4 weeks.