Like garlic and onion, leeks are a member of the allium family, but they have their own unique flavour – quite harsh when raw (only very young leeks are eaten this way) but, when cooked, very delicate, like a mild onion but with a hint of sweetness. Two thirds of their length is white and firm, which are the edible portions, the rest is made up of the leaves or flags, which is usually discarded. Leeks are very versatile but one of the most popular uses for leeks is for adding flavour to stock, two of the world’s most famous soups, Scotland’s cock-a-leekie and France’s crème vichyssoise, are based around them.