I suggest you prepare these as soon as possible, because they are very important to the North African kitchen and are called for in several recipes. Once you’ve tried cooking with them, you’ll want to include them in your cooking forever. Follow the 3-week recipe for the best results, but if time is short, opt for the 5-day version instead, and if time is really short, use good-quality bought preserved lemons. You may occasionally notice a white substance forming on the top of the lemons. Although this substance is harmless, it’s best to rinse it off before using.