For the strudel dough, knead all the ingredients together and cover and leave for about 1 hour.
For the filling mix well the butter and powdered sugar, then stir in the egg yolks one by one. Mix in the quark, sour cream, lemon zest, vanilla sugar and raisins. Finally, beat the egg white until stiff and fold in carefully.
Spread the strudel dough thinly on a floured cloth, spread the filling and roll it up with the help of the cloth.
Lightly grease a baking dish and gently slide the strudel into it with the aid of the cloth.
Bake in the oven at 180 degrees for about 30 minutes, pour the icing over the top and bake for another 30 minutes.
Mix the ingredients together for the icing.
Instead of raisins, you can also mix chopped apples, pears, apricots (apricots) or cherries, blueberries or blackberries into the curd mixture.