Place 625 g of quark in the middle of a damp tea towel. Take the corners of the cloth together and squeeze out some of the curd by turning it (at least 125 ml of liquid should come out). Put the quark in a bowl, mix with breadcrumbs, 2 tbsp. oil, 50 g sugar and egg. Mix 175 g quark, milk, 6 tbsp oil, 100 g sugar and orange peel. Mix flour, salt and baking powder.
First knead with the dough hooks of the hand mixer, then with your hands under the quark-milk mixture and work into a smooth dough. (If the dough is too firm, knead in spoonfuls of water, it should stick, knead in spoonfuls of flour). Roll out the dough into a rectangle (approx. 32 x 39 cm) on a floured work surface. Spread the jam on the rectangle, leaving an approx. 2 cm wide edge. Place the quark filling on a narrow side, leaving a margin of approx. 2 cm on the narrow and long sides. Fold the long sides over 1.5-2 cm towards the middle. From the narrow side, roll up the quark into a strudel and place on a baking tray lined with baking paper with the seam facing downwards. Cut the top of the roll of dough diagonally 4-5 times. Mix egg yolk and 3 tbsp. water. Spread the strudel with it. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 25-35 minutes until golden brown.
From the narrow side, roll up the quark into a strudel and place on a baking tray lined with baking paper with the seam facing downwards. Cut the top of the roll of dough diagonally 4-5 times. Mix egg yolk and 3 tbsp. water. Spread the strudel with it. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 25-35 minutes until golden brown. Remove the strudel, cover with a tea towel and let it cool down. Dust with icing sugar before serving
waiting time approx. 2 hours