These figure most prominently in North African cooking, popping up in dishes such as tagines, and also appear across the Mediterranean and Middle East. The skin softens significantly and becomes much easier to eat. You can buy them in jars or prepare them yourself: make several deep slashes into the lemon, pack the cuts with salt, then layer in a big jar, pressing down and adding lemon juice.
Recipes with preserved lemons
Lamb, chickpea and squash tagine with chermoula and couscous
Red cabbage and preserved lemon tagine