Preheat the oven to 400°F. Line a baking sheet with parchment paper., To make the filling: Grate the apples on the medium hole of a box grater, then transfer to a fine mesh strainer. Squeeze the apples well to remove any excess moisture., Place the raisins in a small, heat-safe bowl. Pour the hot water over them and soak for 5 to 10 minutes. Drain the raisins and squeeze out the excess liquid., Place the soaked raisins, sugars, lemon zest, cinnamon, ginger, and salt in the bowl of a food processor. Pulse until the mixture is fully combined and looks a bit pasty. Add the melted butter and pulse to combine, then transfer to a bowl and stir in the grated apples by hand. Set the filling aside., To assemble: Stretch the strudel dough as described in the recipe. Drizzle with 3 tablespoons of the melted butter, then sprinkle with the bread crumbs. Dab the filling over the bread crumbs and distribute as evenly as you can. Roll up and trim the strudel as the recipe directs, and transfer it to the prepared baking sheet., To finish and bake: Brush the strudel with the remaining tablespoon of melted butter and sprinkle it with turbinado sugar. Bake until the strudel is golden brown, 25 to 30 minutes. Rotate the pan halfway through the baking time. Remove from the oven and cool at least 15 minutes before slicing and serving.