1. Prepare the dough In a bowl, mix flour and salt. Add the egg, warm water, and oil. Knead until the dough becomes smooth and elastic. Cover and let it rest for 30 minutes.
2. Make the filling In another bowl, combine ground walnuts, sugar, cinnamon, vanilla, warm milk, raisins, and lemon zest. Mix well.
3. Stretch the dough Place the dough on a floured cloth and gently stretch it into a very thin rectangle (almost transparent).
4. Add the filling Brush the dough with melted butter and spread the walnut filling evenly over the surface.
5. Roll the strudel Using the cloth, carefully roll the dough into a long log.
6. Bake Place the strudel on a lined baking sheet, brush with melted butter, and bake at 180°C (350°F) for 30–35 minutes until golden.
7. Serve Let it cool slightly and dust with powdered sugar before slicing.
