7 lemons, plus 5 to 7 extra for juicing
4 tablespoons kosher salt
1 tablespoon sugar
2 tablespoons thyme, picked off the stem but not chopped
2 16-ounce canning jars
Wash 7 lemons and then slice crosswise into ¼-inch rounds. Mix the salt and sugar together and toss in the lemon slices to coat. Stack them snuggly in a clean jar or small airtight container. Every 4 or 5 slices, sprinkle in some thyme, and then continue stacking and packing. Fill the jar to the brim with lemon slices, and then pour on the extra lemon juice to fill in any cracks. You want the lemon juice to come right up to the top of the jar, submerging the slices. Screw the lid on tightly.
Keep the jars stored in your fridge for 3 weeks before opening, shaking for a few seconds every 4 days. After 3 weeks, remove the slices as you need them, remembering to rinse the salt off the lemon before using. Preserved lemon will keep in the fridge for months.