Mix flour and salt in bowl.
Cut in shortening thoroughly with pastry blender.
Sprinkle in water, 1 tablespoon at a time, mixing with fork until all flour is moistened and pastry almost cleans side of bowl (1 to 2 teaspoons water can be added if necessary).
Gather pastry into ball; divide into 6 equal parts.
Place each part on 5-inch square of heavy-duty aluminum foil; roll each into circle, about 5 inches in diameter.
Trim edges of foil and pastry to make neat circle.
Shape foil and pastry together into tart by turning up 1 1/2-inch edges; flute.