Ever wondered exactly what a jostaberry is? It is, in fact, a cross between a gooseberry and a blackcurrant – and the best of both. Jostaberries grow on a large bush with leaves and flowers similar to those of blackcurrant bushes, without the sharp needles of a gooseberry bush. The size of small marbles, with bright-green flesh and reddish-black skins, they have a flavour that swings more towards the blackcurrant. Their star attribute is not only their taste but their outstanding performance in the kitchen. When they are cooked for pies, fools and suchlike, their strong, concentrated flavour really shines. You could, of course, substitute blackcurrants in this recipe.

SERVES 6

For the vanilla ice cream

400ml milk
200ml double cream
1 vanilla pod
6 egg yolks, beaten
100g granulated sugar

For the ripple

400g jostaberries
200g granulated sugar

1 Put the milk and cream in a saucepan. Slit the vanilla pod open lengthwise, scrape out the seeds and put the seeds and pod in the pan. Heat slowly, stirring occasionally, until it is just too hot to put your finger in; do not allow it to boil.

2 Meanwhile, whisk the egg yolks and sugar together in a bowl. When the milk mixture is hot enough, pour it on to the eggs and sugar, whisking constantly. Return the mixture to the pan and heat gently, stirring, until it is thick enough to coat the back of the spoon. This can take up to 15 minutes. Remove from the heat and leave to cool, then chill for at least 2 hours.

3 For the ripple, put the berries and sugar in a pan, cover and cook gently, stirring occasionally to dissolve the sugar (there’s no need to top and tail the fruit, as the sauce will be strained once cooked). Once the fruit has split its skins and the juices are flowing, remove from the heat. Allow it to cool a little, then blitz in a food processor.

4 Strain through a sieve to remove the skin and pips, leaving the syrup to drip through until you are left with a dry pulp in the sieve. Cover the syrup and chill for a few hours.

5 Give the custard a good whisk to ensure it hasn’t separated, then churn it in an ice cream machine according to the manufacturer’s instructions. When it is thick and almost frozen, pour the syrup into the machine and allow it to streak the ice cream as much or as little as you wish.

7 Transfer to a plastic container and freeze. Soften slightly before serving.

Recipe from Fern Verrow by Jane Scotter and Harry Astley. Photography by Tessa Traeger (Quadrille).

This recipe features in August's issue of The Simple Things - out 29 July 2015.