Leeks resemble giant spring onions, with green tops and white bottoms. Their mild onion-like flavour goes well in stews and other recipes, most notably potato soup. When purchasing leeks look for crisp ones with the roots still attached, as these are at their height of flavour. In season from late fall into winter, it is possible to freeze them for spring and summer cooking. Frozen leeks become soft and are best served as a component in other dishes or in soup to mask the texture change.
Peel off the outer green leaf and discard. Wash the leek thoroughly under running water as leeks usually have dirt stuck between their leaves. Pat it dry.
Trim off the tough, green top of the leek with a sharp knife. Leave the roots intact.
Wrap whole leaks tightly in cling film or seal in plastic bags. Leeks transfer their aroma to other items in the freezer if they are not sealed well.
Slice the leek into disks if you prefer. Lay the disks in a single layer on a parchment paper covered baking tray.
Place the baking tray in the freezer for four hours or until the leeks freeze. Place the frozen sliced leeks into a tightly sealed plastic bag.
For particularly dirty leeks, make a cut halfway through the length of the leek so you can wash out the dirt inside. Store leeks for up to 3 months in the freezer.
Frozen leeks may darken or lose some of their flavour.