Cut the butter into pieces. Knead flour, icing sugar, butter, 1 egg yolk and salt first with the dough hook of the hand mixer, then with your hands to a smooth dough. Wrap in foil and chill for about 30 minutes. Wash and sort the berries. Pluck currants from the panicles. Grease 6 tartlet cups with lift-off base (approx. 12 cm Ø).
Roll out the dough thinly on a lightly floured work surface and cut out 4 circles (each approx. 16 cm Ø). Line 4 moulds with the dough and press the edges well down. Cut off any excess dough. Prick the cake several times with a fork. Knead the remaining dough again and roll out. Cut out 2 more circles, place them in the remaining moulds and prick them as well. Put the ramekins in a cold place. Mix sour cream, sugar, crème fraîche, vanilla sugar, lemon juice and 1 egg yolk. Fold in half the berries and fill into the moulds. Spread the rest of the berries on top. Bake the Tartelettes in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 20-25 minutes.
Cut out 2 more circles, place them in the remaining moulds and prick them as well. Put the ramekins in a cold place. Mix sour cream, sugar, crème fraîche, vanilla sugar, lemon juice and 1 egg yolk. Fold in half the berries and fill into the moulds. Spread the rest of the berries on top. Bake the Tartelettes in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 20-25 minutes. Open the oven door. Take the Tarteletts out of the oven after about 20 minutes and let them cool down on a cake rack
Waiting time approx. 1 hour