To make the dough, in a medium bowl, stir together the flour and salt. Make a well in the center and add the oil, egg yolk and water. Using a fork, stir in a circular motion, gradually moving outward to incorporate flour, until a shaggy dough forms. Using your hands, bring the dough together and knead, swiping along the edges of the bowl to incorporate dry bits, until the dough forms a cohesive ball. Lightly flour the counter and turn the dough out onto it.

Continue kneading. Every 10 to 15 turns, lift the dough off the counter and throw it firmly against the counter; this is called “crashing.” Do this a few more times, then alternate sets of kneading and crashing in the same way until the dough is taut and smooth, with a clay-like quality, 7 to 10 minutes. Form into a ball, cover with plastic wrap and let rest at room temperature at least 30 minutes or up to 1 hour while you prepare the filling.

Meanwhile, make the filling. In a medium bowl, stir together the sugar, cinnamon and salt. In a 10-inch skillet over medium, toast the walnuts, stirring, until fragrant and lightly browned, about 3 minutes. Transfer to the bowl with the sugar mixture. In the same skillet over medium, toast the breadcrumbs, stirring, until golden brown, about 2 minutes. Transfer to the bowl with the sugar mixture and stir. Wipe out the skillet.

In the same skillet over medium, melt the 71 grams (5 tablespoons) butter. Cook, stirring, until beginning to brown, 2 to 3 minutes. Pour the butter over the sugar mixture; stir until evenly moistened. Peel, core and cut the apples into ½-inch cubes; set aside. Heat the oven to 400°F with a rack in the lower-middle position. Line a rimmed baking sheet with kitchen parchment. Mist the parchment with cooking spray.

Fold a clean tablecloth into a 3- to 4-foot square. Lightly dust it with flour. Place the dough on the cloth and roll it into a rough 12-inch round. Holding the dough aloft, with the tops of your hands underneath it, as if shaping pizza dough, gently stretch the dough while rotating. Continue stretching as evenly as possible until the dough becomes too unwieldy to rotate, then lower the dough near the center of the tablecloth and smooth any folds. The edges will be slightly thicker than the center.

Using both hands and working around the circumference of the dough, gently stretch and pull the dough into a 2½-by-2-foot rectangle, with a long side facing you; it’s OK if there are a few small tears. Using a sharp paring knife, trim off and discard the very outer edges, as they will remain thicker. Brush the surface with 2 tablespoons melted butter, making sure the far edge is coated.

Toss the apples with the butter-sugar mixture. Scatter the apple filling in an even layer over the dough, leaving a 1½-inch or so border around the edges. Using both hands and a wide grip, lift the edge of the cloth closest to you to start rolling the dough away from you, then continue lifting the cloth until the dough has formed a log. Twist the ends of the log to seal, then, if needed, trim the ends so there is only about 1 inch excess. Carefully transfer the log to the prepared baking sheet, making sure the seam is down, then bring the ends together to form a ring shape; it’s OK if the ends don’t touch.

Lightly brush the Strudel with the remaining 1 tablespoon melted butter. Bake until golden brown, 30 to 35 minutes, rotating halfway through. Cool for 10 minutes, then carefully use the parchment to lift the Strudel to a cutting board. Slide the parchment out from under the Strudel. Serve warm, dusted with powdered sugar and with whipped cream on the side.