• Crush the strawberries in a large bowl with a wooden spoon.
• Stir in the sugar and allow to stand in a warm kitchen for about 1 hour, stirring occasionally until the sugar has dissolved.
• Add Certo and stir well.
• Add the lemon juice and continue to stir for 2 minutes.
• Ladle into small containers, cover securely.
• Leave to stand in a warm place for 48 hours and then freeze.

MAKES 3lb OF JAM.