1. Place 2 cups of blackcurrants in a kitchen whizz and blend. Transfer to a pot and add ½ cup sugar and the zest of 1 lime or lemon and 2 tablespoons of juice of lime or lemon. Simmer for 5 mins.

2. Beat 4 egg whites with electric beater until you have soft peaks. Gradually add 1/2 cup sugar and beat until stiff glossy peaks form when the beater is lifted. On low speed, gradually add hot fruit purée and beat until cool and very thick, about 10 mins.

 3. In separate bowl, beat 1 cup of cream to soft peaks. Fold into egg white mixture using a large flat spoon until evenly blended.

Place in a freezing container, cover and freeze until firm, about 4 hrs.

Will keep in freezer for several weeks. Makes 1 litre.