Summer berry meringue roulade

1 Put 75g raspberries, 100g redcurrants and most of the lemon juice (reserving 1 tsp) in a blender; whizz until smooth. Put 75ml of this purée in a pan with 100g sugar, 3 egg yolks and the butter. Heat gently, stirring until combined and thickened (8-10 minutes). Pour into a bowl, cover the surface with baking parchment and chill.

2 Preheat the oven to 140°C, gas mark 1. Grease a 26cm x 38cm Swiss roll tin and line with baking parchment. In a stand mixer (or using electric beaters), whisk the egg whites to stiff peaks. Continue whisking while slowly adding ½ of the remaining 225g sugar, 1 tbsp at a time. Fold in the rest of the sugar, followed by the reserved 1 tsp lemon juice, the cornflour and vanilla. Spread the meringue mixture out on the lined tin and bake for 1 hour, until golden and crisp on the outside. Use the parchment to lift the meringue onto a wire rack to cool.

3 To assemble, whisk the cream to soft peaks. Lay a piece of baking parchment over the meringue, then invert the meringue onto it. Peel the parchment off the back. Spread the cream on top,  then spoon over the berry curd. Scatter over ⅔ of the remaining fruit. Carefully roll up the roulade from one short end. Drizzle over the remaining purée and scatter over the remaining fruit.