In the bowl of a stand mixer combine the flour and salt. With the paddle on low, add the lukewarm water, oil, and vinegar until the mixture forms a soft mass. Swap to the dough hook and knead on medium until a smooth, supple ball forms.

Turn the dough onto a clean surface and hand-knead 2–3 minutes until silky. To strengthen the gluten, gently slap the dough a few times on the counter, then shape into a ball. Place it in a lightly oiled bowl, rub a little oil over the top so it won’t dry, cover tightly with plastic wrap, and let rest 60–90 minutes.

Preheat the oven to 375°F (190°C). Place the raisins in a bowl of hot water and let them soften for about 10 minutes, then drain. Peel, core, and slice the apples thinly. Combine the granulated sugar and ground cinnamon in a small bowl. Lay a clean tablecloth or large sheet over your work surface to catch and support the dough while stretching.

Move the rested dough to a dry surface and cut it in half. Keep one half covered. Shape the other half into a smooth ball and roll it out as thinly as possible with a rolling pin.

Carefully transfer the rolled dough onto the prepared tablecloth. Using your knuckles or the backs of your hands (remove jewelry first), gently lift and stretch the dough outward a little at a time. Work from the center toward the edges, letting the dough’s own weight help it thin; continue until the dough is nearly transparent and you can see the cloth pattern through it. Trim or gently pull away any thick outer bands.

With your hands or a very soft brush, spread about 1/4 cup of the melted butter evenly over the stretched dough, leaving a 1-inch border. Sprinkle half the breadcrumbs across half the dough, then layer half the apple slices on top. Scatter half the drained raisins over the apples and dust with half the cinnamon-sugar mixture.

Fold the short edge of the dough over the filling, then fold in the sides to form an envelope that keeps the filling contained. Grasp the tablecloth at the short end and lift, guiding the dough so it rolls itself into a tight log; keep lifting and rolling until the strudel is completely rolled.

Transfer the log to a parchment-lined baking sheet with the seam side down. Repeat the rolling and filling process with the remaining dough and filling, reserving about 1/4 cup of melted butter. Brush the tops of both strudels with the remaining melted butter.

Bake the strudels in the preheated oven for 25–30 minutes, or until the pastry is a deep golden brown. Remove from the oven and let them cool for 10–15 minutes so the filling sets.

Dust the cooled strudels with powdered sugar, slice, and serve warm or at room temperature.