This is actually an Austrian recipe (I picked German cuisine only because there was no option for selecting Austrian, and German was the closest cuisine choice).
Strudel is a traditional Austrian pastry, and a specialty in Vienna in particular. It's a dessert pastry that's usually topped with whipped cream, vanilla sauce, or vanilla ice cream for an additional sweet touch.
To make the dough: Place the flour in a bowl with the salt and add the water, then the oil. Stir with a spoon until it comes together and you can work it with your hands. Knead the dough until it is smooth and tacky, but not sticky, about 5 minutes. If you need to add more flour, only add it 1 teaspoon at a time, and rework the dough after each flour addition (before adding more). Form the dough into a smooth ball, brush it with a little oil and place it back in the bowl for about 1 hour at room temperature. Covering the dough with plastic wrap is fine, too.
To Make the First Filling: Heat the butter in a pan until foaming and add the breadcrumbs. Toast them, stirring constantly, until they are medium brown. Let cool.
To Make the Second Filling: Heat the raisins for 30 seconds in microwave oven. Then soak raisins in rum (or orange juice); set aside until ready to use.
Peel, core and chop the apples into small pieces. Add the sugar, lemon juice, lemon zest, cinnamon and nutmeg. Place raisins in colander to allow excess liquid to drain. Add to apple mixture, and mix well.
Roll out the dough on a lightly floured board to about 9 inches by 13 inches. Lightly flour a clean towel with no nap, place it over the dough, grab both (towel and dough) and flip over so towel is on bottom and dough is on top. Straighten both, as necessary. Using your hands, gently stretch the dough thinner on all sides, working your way around the sheet of dough. Stretch it until it starts to look translucent in spots. Let it rest a minute and stretch the areas you think are too thick, again. Brush dough with melted butter.
Spread the first filling (toasted breadcrumbs) over 2/3 of the dough and pat down evenly. Spread second filling (apple/raisin mixture) over the other 1/3 of the dough. With kitchen shears, snip off any thick edges of dough, so dough is more uniform. Using the towel, fold one side of the dough over the filling. Brush exposed dough with melted butter. Fold in ends of dough like a burrito. Fold other side of dough up and over filling to form a loaf. Brush with butter.
Use the towel to lift the strudel to a parchment-lined baking sheet. Gently roll strudel onto parchment paper so that the seam-side is down. Brush melted butter over the dough. Bake at 400° for 20 minutes. Reduce heat to 350° and bake for 40-60 minutes longer.
Remove strudel from oven, brush with melted butter again, then sprinkle with powdered sugar while still warm. Transfer to a serving platter with a large spatula (or two). Cut into 1 1/2 inch wide slices with a bread knife or serrated knife. Serve with your choice of whipped cream, vanilla sauce, or vanilla ice cream.