Leeks aren’t green onions, but they’re in the same family. Leeks are milder and sweeter, with a much gentler in flavor than green onions which can be pungent at times. You can use the dark green leaves are flavoring broth, but only the white and tender pale green portions are used as a vegetable. Leeks need to be well-cleaned; growers pile dirt around the shoots of the leek while it is growing so the white portion is not exposed to sunlight.
To prepare the leeks, remove the green stems where it naturally bends, as the green stems can be bitter. Cut off and discard. Slice each leek lengthwise, leaving the bottom inch intact, then turn 90 degrees and slice lengthwise again. Rinse well.