For the Erdäpfel-Kletzenstrudel, sift the flour with baking powder and knead with the strained potatoes, butter, powdered sugar, egg yolks, a pinch of salt and lemon zest to a dough. Let it rest for a short time and then roll out into a rectangle. Spread with the prepared stuffing, roll up and place on a baking tray lined with baking paper.
Prick the strudel with a fork and brush with egg. Bake in the preheated oven at 180°C for about 50 minutes.
For the Erdäpfel-Kletzenstrudel, remove the stems from the soaked and then softly cooked currants, remove the blossoms and mince. Mix with curd cheese, honey and grated and roasted hazelnuts. Season with a pinch of salt and cinnamon. If necessary, add a little water for cooking the cucumbers.