In the bowl of a food processor, put the flour, salt and sugar, and pulse for a few seconds to combine. Add the butter or margarine and pulse until the mixture has the consistency of coarse cornmeal. Add 2 tablespoons of water and pulse until the dough pulls away from the sides and forms a ball. Shape the dough into a disk, wrap in cellophane, and put in the refrigerator for 30 minutes.

Preheat the oven to 220C (425F). Roll the dough into a circle 25cm (10-inches) in diameter. Place the dough into a 22cm (9-inch) tart pan with a removable bottom. Prick the bottom and sides of the dough with a fork and bake blind for 8 to 10 minutes or until lightly browned. Set aside to cool slightly.

Lower the oven temperature to 200C (400F). Spread the apple sauce over the tart base and place the sliced apples on top in a circular pattern. Bake for 30 minutes and serve at room temperature.