Cut off dark green bits and hairy roots at the other end ~ wash the remainder thoughly as they can have some soil between the tighly packed leaves.
Melt a little butter in a pan, slice leeks thinly in rounds and toss them in the butter until they are bright green, serve with cheese sauce or just melt cheese over them under the grill.
Alternatively. Prepare as before then slice them in half lengthways. Place into boiling water and cook for ten minutes. Serve with sauce as before.
Or if you want to get really cheffy prepare as before then thinly slice them lengthways into long strips about 2mm wide. pick up a large handful and form into a sort of birds nest shape, Drop into very hot deep fat and fry until crisp and brown. Take out of fat and you should have what looks like a tangle of thin brown grass (as in a birds nest) Serve as an accompaniment to steak, chicken breast or anything that takes your fancy.