Select beans that are firm and pale to bright green. Avoid any that are flabby or discoloured.

Top and tail, then slice or cut into diagonal pieces, about 2.5 cm/1 in long.

Blanch in boiling water for 2 minutes. Drain and plunge immediately in a bowl of iced water to cool. Drain again and dry on kitchen paper, then pack in convenient quantities in polythene bags. Remove the air, seal, label and freeze. Storage time: 12 months.