On a stable cutting board, trim the root end off and discard. Next, remove 5 inches of the top dark green leaves, leaving the lighter green leek leaves. (The dark part is tough but is great in chicken stocks and bone broths!)
Then, from the root end slice up all the way through the leek but leave the top end connected, this is so you can soak and wash the dirt but not have leaves everywhere!
Once most of the dirt is removed slice all the way through so you have two halves.
In a large bowl of clean cool water, rinse the leek halves and change the water several times.
Fan the leaves open under water to be sure they are clean. And keep changing the water until clear.
Once clean, move to a cutting board. Now slice all the way though the leeks, and slice into thin strips for your recipe.