First, cut off the root and remove the hard, dark green leaves. Trim the dried ends off all the remaining leaves, cut lengthwise, and then cut again according to your recipe instructions. (Usually only the white and very pale green parts of the plant are used.) Rinse the cut leeks in a bowl of cold water, drain into a colander, and rinse again with running water. All dirt, sand, and tough, inedible leaves will be gone, leaving you with perfect leeks ready to be used in any recipe.