In a large mixing bowl, combine the flour and salt. Make a well in the center and add warm water, oil (or melted butter), and the egg (if using). Stir until the dough forms. Knead on a floured surface for about 10 minutes until smooth and elastic. Cover with a damp towel and let it rest for 30-60 minutes.

On a floured surface, roll out the dough into a rectangle. Using the backs of your hands, stretch it gently from the center outward until it is paper-thin. Be careful not to tear it.

Peel, core, and slice the apples thinly. Toss them with sugar, cinnamon, lemon juice, and raisins (if using). Let sit for 10 minutes to release juices.

Preheat the oven to 375°F (190°C) and line a baking sheet with parchment paper.

Sprinkle a thin layer of breadcrumbs over the stretched dough to absorb excess moisture. Evenly distribute the apple filling, leaving a 2-inch border around the edges. Fold in the sides and roll the strudel tightly.

Place the strudel seam side down on the baking sheet. Brush generously with melted butter. Bake for 35-40 minutes or until golden brown and crisp.

Allow the strudel to cool slightly before slicing. Dust with powdered sugar and serve warm with vanilla ice cream or whipped cream.