Wash the currants, drain and pluck them from the stalks. Sort the raspberries. Mix sour cream, vanilla sugar, lemon juice and sugar. Unroll the base and place on a baking tray with the baking paper.
Spread the sour cream on top, then cover with berries. Bake the cake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 15-20 minutes. Remove cake from oven and sprinkle with pistachios.