Leeks are root vegetables that look quite similar to onions, to which they are related. Their flavor is onion-like but much milder. People who avoid leeks because they don't like onions should try them -- their flavor is mellow and not overpowering, and many onion-haters love leeks. Leeks don't form much of a bulb on the end of the root as onions do. Instead, they remain cylindrical, with perhaps a slight bulge at the end. The part of the leek that is under ground remains tender and white, while the part exposed to the sunlight becomes tough and fibrous and not very good eating. To maximize the edible part of the leek, farmers mound the dirt up around the sprouting plant; this keeps more of it underground and white, but also means that dirt often gets between the layers, so leeksleeksleeks need careful cleaning before cooking. Leeks are most commonly used in soup, most notably in vichyssoise, a lovely soup composed of potatoes and leeks and served cold -- excellent for summer day lunching. If you have a favorite potato soup recipe, try adding some sliced leeks next time you prepare it -- leeks, potatoes and carrots in a chicken broth is about the best soup there is. Leeks are also edible raw, and can impart a great crunchy flavor to salads or when eaten with a dip. Cut leeks in half lengthwise and rinse thoroughly to remove and dirt or grit, then add to a platter of crudites. Leeks are a great source of fiber in your diet, and may actually help lower cholesterol. They're also packed with important vitamins and minerals, including potassium, so if you are trying to increase your intake of potassium, add a few leeks to your week. According to Welsh tradition, back in the days before military uniforms, the Welsh fighters were instructed by their king to distinguish themselves from the enemy by fixing a leek to their helmets. Whether because of this legend, or for older reasons, the leek is one of Wales' national symbols, and is worn on the lapel in honor of St. David, Patron Saint of Wales, on his Day.