Unroll the puff pastry on a baking tray (approx. 32 x 37 cm) with the rolled up baking paper. First fold in both long edges 0.5 - 1 cm, then fold over another 3-4 cm to the middle. Cut the edges of the dough with scissors at a slight angle at approx. 2 cm intervals. Prick the middle pastry base several times with a fork. Bake in the preheated oven (electric range: 225 °C/ convection oven: 200 °C/ gas: level 4) for 10-15 minutes until golden brown. Let the finished puff pastry cool on the baking tray.
In the meantime, sort out the raspberries. Place the sour cream, sugar and vanilla sugar in a mixing bowl and whisk until thick and creamy. Cut puff pastry strips into 6-7 pieces. Spread a blob of sour cream on each strip and cover with raspberries. Arrange the pieces on a plate and serve sprinkled with icing sugar