First prepare the dough for the Wiener Tascherln. Knead all the ingredients together and leave to rest in a cool place for 2 hours.
For the filling, briefly boil the berries with the jam, mix and let cool slightly.
Roll out the dough on a floured work surface to a thickness of 3 mm. Cut out 6 cm Ø discs. Spread the filling in the center, brush the edges of the dough with egg white, fold the discs together, press the edges with fork tines.
Place on a baking tray covered with baking parchment, brush with egg white and bake at 180 degrees in a preheated oven for 15 minutes until golden brown. Serve while still hot.