This is my favourite way of cooking leeks – very gently, in their own juices and served as a vegetable, particularly at the end of winter when there's not an awful lot else available.
This recipe is from Delia's Complete How to Cook. Serves 2
When the leeks are trimmed and washed, cut them all the way through vertically, then chop them into 1 inch (2.5 cm) pieces.
Now place a small frying pan over a medium heat, add the butter and let it melt – it needs to lightly coat the surface of the pan. Now add the leeks and some seasoning, stir them around, then turn the heat down to low and let them cook gently for about 5 minutes without a lid, stirring them 2 or 3 times. There will be quite a lot of juice that collects in the pan, so use a draining spoon to serve.