Preheat the oven to 190°C, fan 170°C, gas 5. Line a 30cm x 20cm tin with baking parchment.
In a large bowl, whisk the egg whites to medium peaks, about 3-4 minutes. Gradually whisk in the sugar, then fold in the cornflour, vinegar and lemon zest.
Pour into the prepared tin. Bake for 15 minutes, until there’s a crust on top. Take out of the oven and leave to cool in the tin for 5 minutes.
Dust a large piece of baking parchment with icing sugar. Gently flip the tin to turn the roulade out onto the parchment; peel the paper from the base.
When completely cool, spread with the lemon curd and scatter over the berries. Roll up the roulade from the long side and transfer to a plate. Decorate with the extra berries and a dusting of icing sugar. Slice to serve.