Prepare the apple mixture. Peel and cut the apples into small pieces, place in a deep bowl, add half the sugar, 1 tbsp flour and cinnamon. Mix thoroughly and let the mixture sit for 20 minutes.
Prepare the nuts. Chop the nuts with a knife or blender into small pieces so that they still differ slightly in size. Add the breadcrumbs, remaining sugar and mix thoroughly.
Roll up the strudel. Sprinkle the work surface with the rest of the flour and roll out the dough on it into a rectangle. Step back 5 cm from one edge and spread the nut mixture across the sheet, and then spread the apple mixture on top of it. Cover the filling with dough from the edge closest to where you stepped back, and then roll up tightly.
Prepare the strudel. Beat the egg. Place the strudel on a baking sheet covered with parchment paper, brush with egg. Place the strudel in an oven preheated to 180 degrees and bake for 30-40 minutes until golden brown.