The whole leek is eaten, the white and the green. The white is tender and is cooked melted, in a soup or a tart; the green, firmer, flavours a stock or a blended soup. What matters is washing it properly, because soil hides between the leaves.
Straight, with a firm white and green leaves standing well, not yellowed.
Cut the roots and the tips of the damaged leaves. Split the leek in two lengthwise, stopping three centimetres from the base so it holds together. Rinse under cold water, spreading the leaves, the soil comes out.
Three minutes, washing included.
In the fridge, in the vegetable drawer, a week. Cooked, two or three days. Cut and blanched two minutes, it freezes.
The page "How to boil and steam vegetables": leek pieces in vinaigrette.
Easy