Position knife blade in food processor bowl; add flour and salt. Top with cover, and process pulsing 3 or 4 times or until combined. Add shortening to flour mixture. Process pulsing 5 or 6 times or until mixture resembles coarse meal. With processor running, slowly add water (1 tablespoon at a time) until dough begins to form a ball and leaves sides of bowl. Cover and chill 30 minutes. To fit into pieplate, roll dough to 0 cm thickness on a lightly floured surface. Place in a 23 cm pieplate; trim off excess pastry along edges. Fold edges under and flute. For baked pastry shell, prick bottom and sides of pastry generously with a fork; bake at 220ºC or 10 to dozen ----