How to make
Saute the finely chopped onion in the oil. Add the chopped mushrooms and the mince you've diluted with a little water.
Before removing the pot from the stove, add the flour which you've dissolved with a little water, to thicken the filling.
Season with black pepper and if necessary add salt. Roll out the puff pastry (it needs to be at room temperature) into a thin sheet.
Cut the edges on both sides into strips. Put some filling in the middle, arrange pieces of Edammer on top and twist the dough.
Smear it with yolk and bake in a preheated oven until golden.
