Clean the lemons thoroughly to remove any dirt, then chop into quarters, lengthwise. Cover the bottom of a sterilized Mason jar with 1 tablespoon salt and top with 4 lemon quarters, pressing them down as you pack them in to release as much juice as possible. Cover lemon slices with another tablespoon of salt. Repeat until the jar is full, finishing with a final tablespoon of salt. If using spices, tuck the cinnamon stick, bay leaves, and cloves into the sides of the jar as you go. Make sure the top of the lemons are covered with lemon juice (add more juice if needed) before sealing the jar.
Seal the jar and store at room temperature for at least 4 weeks, shaking occasionally to distribute the salt. Once opened, store the jar in the refrigerator for up to 6 months. To use, take a lemon from the jar and rinse it well to remove the salt. Discard seeds and pulp (if desired).
Serving Ideas: Preserved lemons can be used in place of lemon zest or lemon juice in recipes. Or, mince finely and add to couscous or yogurt; use in a homemade vinaigrette; mince with herbs and add to homemade butter; chop and add to soups and stews; mince and cook with butter and wine to make a lemony beurre blanc sauce for fish; chop and mix with olive oil and herbs to rub on chicken before roasting; slice and add to sautéed greens like kale, spinach, and chard; or roast veggies like asparagus, broccoli, and green beans with chopped preserved lemons.