Leeks are a member of the onion, or allium, family, which includes chives, shallots, garlic, and scallions. They have a strong, unpleasant taste eaten raw, but develop a silky texture and sweet flavor when cooked, the perfect foundation for soups, stews, and side dishes.
Grown in sandy soil, the white portion of a leek is deeply embedded to prevent it from turning green (photosynthesis). As a result, leeks always have dirt hidden between the layers and need a thorough rinsing.
The tough, dark green leafy tops are not used in recipes, however, it’s worth cutting through that top lengthwise to see if there are any usable portions hidden in the middle. As the leek grows, the portion of the leek that’s closer to the surface begins to turn a faint green. Use this portion, some of the inner green top leaves, and the white for most recipes.
Occasionally, however, only the pure white portion is used in a recipe where the green color is undesirable, such as Vichyssoise.
As a rough estimate, for every 3 inches of a leek that’s about 2 inches in diameter you will get 1 cup of thinly sliced leeks.
How to Trim and Clean Leeks
Remove the green tops and slice in half lengthwise to see if there are tender, usable green leaves. Toss the dark, tough greens.
Some recipes, such as poached leeks, cook the leeks in two long halves. To prepare the leek, cut off the roots but leave the center core to keep the layers together. Slice the leek in half lengthwise stopping just before the core. Rinse thoroughly and dry. Proceed with the recipe.
Other recipes ask for sliced leeks. Remove the greens as instructed above and cut off the entire root end. Slice the remaining leek in half lengthwise and again lengthwise.
Thinly slice the leeks and place in a cold-water bath.
Swish the leeks around and rub them against each other with your hands to loosen any grit.
Use your hands or a hand strainer to remove the leeks into a strainer or clean bowl.
Drain the water, rinse the bowl, and refill with cold water.
Repeat the above steps until there is no grit left in the bottom of the bowl.
How to Julienne Leeks
Cut off the roots but leave the center core to keep the layers together. Slice the leek in half lengthwise stopping just before the core. Rinse thoroughly and dry. Remove one layer and fold in half lengthwise if small or in quarters if long. Thinly slice the leek.
This shape is perfect for frizzled leeks, which are dipped in a little flour, deep fried, and used as a garnish.