Very finely slice it. Grate some carrots. Spray a pan with frylight and cook the leek and onions until soft. It's lovely with some salmon and mashed potatoes or pork steaks.....
Otherwise, slice your leek finely, fry in frylight. Add a crushed garlic clove, add a spoon of 0% fromage frais or creme fraiche. Lovely with grilled meat or fish.
Or, boil your leek until tender. Put it in a dish and pour over some low fat salad dressing - vinaigrette. Allow to cool and eat as a starter.