Leeks are a root vegetable, much like onions, that require cleaning and trimming before they can be used. Because of the way the leek grows in the ground, sand and dirt must be removed from the layers before the leek is cooked. Once you have trimmed your first leek, any remaining leeks you need for the meal or a future meal will be a simple task to accomplish.
Cut off all but the top 1 to 1 1/2 inches of green leaves from the top of the leek.
Cut off the root end of the leek.
Remove the outer layers of the leek by peeling the layers away from the leek until you reach the creamy, white inner layers.
Slice the leek in half to expose the layers. Pull apart the layers and rinse under cold, running water. The leek is now trimmed and ready to use in recipes.