We tend to think of salt-preserved lemons as being Moroccan, though they are popular throughout North Africa. They are offered as a side dish straight from the pickle jar or are cut up and added to stews to give them a sharp, astringent edge. In this context, a little goes a long way and a heavy hand will result in an inedibly salty dish. They are easy to make and go particularly well with lamb. Always use ripe lemons - or limes, which can be salt-pickled in exactly the same way.