Freezing is only worth doing if the leaves are to be served as a vegetable, as they go limp when defrosted. Select crisp, firm heads with white stalks and greenish-yellow leaves. Avoid any that appear flabby.

Wash, dry on kitchen paper and finely shred.

Blanch in boiling water for 3 minutes. Drain and plunge immediately in a bowl of iced water to cool. Drain and dry again. Pack in convenient quantities in polythene bags. Remove the air, seal, label and freeze. Storage time: 4 months.