For dough: In a medium bowl, stir together flour and salt. Add 5 tablespoons (75 grams) water, oil, and vinegar; stir until a shaggy dough forms. Turn out onto a lightly floured surface, and knead until dough becomes soft, elastic, and only slightly tacky. (This can take up to 10 to 12 minutes.)

Lightly oil another medium bowl. Place dough in bowl, turning to grease top. Cover and let rest at room temperature for 2 hours, or refrigerate up to overnight.

For bread crumbs: In a small skillet, melt butter over medium heat. Add bread crumbs and sugar; cook, stirring frequently, until bread crumbs are golden brown and fragrant. Let cool completely before using.

For filling: In a small bowl, combine raisins and rum. Cover and let stand for at least 30 minutes or up to 2 hours.

In a large bowl, toss together apples and lemon juice. Stir in soaked raisins and rum, sugar, walnuts, cinnamon, and salt until combined.

Preheat oven to 375°F (190°C). Line a rimmed baking sheet with parchment paper.

Line a table or counter with a large clean kitchen towel or tablecloth, and lightly dust cloth with flour. On prepared cloth, roll dough into about a 6-inch square. Using the back of your hands, gently lift and stretch dough. Place on cloth; gently tug and stretch into a 22x18-inch rectangle, with one short side closest to you. (Dough should be thin enough to see the pattern of your cloth through it.) Using a pastry wheel, trim off thicker edges of dough, about ½ inch from all sides.

Sprinkle about half of melted butter onto dough; gently brush butter to spread out. Sprinkle bread crumbs into a 3-inch-wide rectangle that is 4 inches up from bottom of dough and 2 inches inward from both sides of dough. Pile apple mixture onto breadcrumbs, leaving any liquid in bowl. Pack apples tightly together.

Fold bottom border of dough over apple filling, gently stretching to cover. Using cloth to help you, turn and roll up dough and filling into a log. Pinch and tuck ends of dough under log to seal. Place, seam side down, on prepared pan. (Use the cloth as a sling to help transfer strudel to pan.) Brush remaining melted butter onto dough. 10. Bake until golden brown, 40 to 45 minutes, rotating pan halfway through baking. Let cool on pan on a wire rack for 15 minutes. Serve warm or at room temperature with Crème Anglaise. Store in an airtight container for up to 2 days.