1Preheat oven to 180°C. Combine sugar, cinnamon, and salt in a large bowl; set aside 3 tablespoons of sugar mixture.
2Peel and core apples; cut into quarters, then cut into thin slices. Toss with lemon juice; stir into sugar mixture and breadcrumbs.
3Brush 1 sheet of Pampas Filo pastry sheet with butter, and sprinkle with 1 teaspoon reserved sugar mixture.
4Top with remaining 5 sheets, layering with butter and sugar mixture. Scatter filling on filo, leaving a 1/2-inch border. Starting with a long end, roll up to enclose filling. Tuck in the two ends and place strudel, seam side down, on a lined baking tray. Brush top with remaining butter; sprinkle with remaining sugar mixture.
5Bake until golden brown and cooked through, 45 to 50 minutes. Let cool on a wire rack for 10 minutes. Dust with icing sugar and cut into slices. Serve warm with whipped cream or vanilla custard.