Rinse leeks under cool running water to remove grit between layers
Trim off the dark green tops (save for stock if desired)
Trim off the root end
Slice leeks lengthwise in half
Rinse again between layers to ensure no remaining sand
Cut into half-moons or thin slices, depending on your recipe
For rings: slice crosswise into rounds
For julienne: cut lengthwise into strips, then slice into matchsticks
For diced: cut crosswise into half-moons, then turn and dice into small pieces
If using whole: cut only as needed (lengthwise slices or crosswise rounds)