1Heat oven to 425°F. In medium bowl, mix flour, 1 teaspoon sugar, 1/4 teaspoon salt and the oil with fork until well mixed. Stir in milk, 1 tablespoon at a time, tossing with fork until all flour is moistened and pastry almost leaves side of bowl. Shape pastry into a ball, using your hands. Press pastry in bottom and up side of 9-inch glass pie plate; flute as desired or press pastry to top edge of pie plate with fingers or fork.
2In medium bowl, beat egg whites slightly with wire whisk or egg beater. Beat in remaining filling ingredients. Pour filling into pastry-lined pie plate; carefully place on oven rack. Bake 15 minutes.
3Reduce oven temperature to 350°F. Cover edge of pie crust with 2- to 3-inch strip of foil to prevent excessive browning. Bake about 45 minutes longer or until knife inserted in center comes out clean. Cool on cooling rack at least 1 hour before serving. After cooling, pie can remain at room temperature up to an additional 5 hours, then should be covered and refrigerated.