Prepare the dough: In a bowl, combine flour and salt. Add water and oil, mix until a dough forms. Knead for 5-7 minutes until smooth. Cover and let rest for at least 30 minutes.
Prepare the filling: In a large bowl, combine sliced apples, raisins, walnuts, breadcrumbs, sugar, melted butter, and cinnamon. Mix well.
Assemble the strudel: On a lightly floured surface, roll out the dough very thinly into a large rectangle. Brush with melted butter. Spread the apple filling evenly over the dough.
Carefully roll up the dough, starting from one end. Place the strudel on a baking sheet lined with parchment paper. Brush with melted butter.
Bake at 375°F (190°C) for 40-45 minutes, or until golden brown. Let cool slightly before slicing and serving.
Notes
Serve warm with vanilla ice cream or whipped cream.