Most recipes call for just the whites of leeks, which means you are throwing away most of the vegetable. You can use the green tops to make stock, but there are also recipes that call for the entire leek. Even when using the whole leek, trim off the very top, which is often cracked or bruised, and trim off the very bottom. Wash leeks thoroughly. Young, thin leeks are the best ones to serve whole. Thick leeks are often tough, and the green stalks can be stringy.
If you are grilling leeks, you can use the entire vegetable. First, slice leeks in half lengthwise. Steam them in a vegetable steamer or par-cook in a microwave until just tender, about three minutes. Brush with olive oil and salt, then grill. Let them get nice and brown on one side, about seven minutes, then turn and grill the other side until brown. You can do this over a gas or charcoal grill. If using gas, have the grill turned to medium-high. The grilled leeks go very nicely with a mustard vinaigrette: 2 tbsp. of Dijon mustard whisked into a half-cup olive oil and one-eighths cup balsamic vinegar. For a different twist to a grilled leek dish, shave Parmesan cheese on top, then add chopped black olives and sliced hard-boiled eggs. If you are grilling four leeks, you will need an ounce of Parmesan cheese, a quarter-cup of black olives and two hard-boiled eggs.
Braising is cooking in water. You will need a large pan that can hold the whole leeks. Put 3 quarts of water in the pan and add two sliced carrots, one sliced celery stalk, a bunch of parsley and some peppercorns. You can also add a quarter-cup of white wine. Cut four leeks in half lengthwise and add them to the pan. Lower heat to a simmer and cook about 20 minutes, until tender. Serve leeks with olive oil and chopped herbs. Strain the braising liquid and save for soup stock.
Just the Tops
Since leeks are a member of the onion family, and similar to scallions, you can use the tops of leeks, leftover from many leek recipes, in Asian stir-frys and other Asian dishes. If a recipe calls for both onions and scallions, you can substitute an equal amount of the green leek tops. Just be sure to cook the leeks slightly longer than the scallions, because the greens can be a bit tough. If you are making a dish such as sesame noodles or Pad Thai and want to use the leek tops as a garnish, steam them for a minute or two first to soften them. They will impart an onion flavor, and you will use up a part of the vegetable that you otherwise would have thrown away.