Scottish leeks have a long green part, while English leeks are blanched to higher up the stem, meaning they have more white.
Choose small or medium sized leeks, not yellowing or
dried out looking. The root base should not be slimy or
Cleaning whole leeks is a tricky business. Trim off the coarse green leaves, and slit the leek as far down as you can without it starting to fall apart. Wash it in copious amounts of running water. You will also have a chance to check if the leek has a fat flower stem running through the middle. This is common in large leeks, and even apparently slender leeks may be concealing one, since unscrupulous merchants sometimes strip the outside layers of fat leeks away if they are looking tired. If you do find one, it will need cutting out unless the leeks are to be pureed. To clean sliced leeks, tip them into a large bowl. Run cold water on top, agitate well, separating the rings, then leave for a few minutes. The grit and dirt will sink to the bottom of the bowl. Scoop the leeks out with your hands, leaving the grit behind at the bottom of the water. Don't drain them in a colander, or the dirt will resettle on top of the leeks.
Despite their up and down history, leeks are a fine part of the culinary repertoire, both cooked by themselves or as a replacement for onions in a stew. 'The flavours of a soup or stock made with leek will seem more integrated and refined than those of one made with onions alone.