This is a perfect pie for the holidays or the summer rhubarb harvest . The filling comes up a crimson red and if you sugar the crust cut outs it will look like snow or frost on them. Don't let anyone peek at it before dessert and then get ready for the "ooooooooh's" . Especially if it's served by candle light because the sugar on the crust will sparkle.
In a medium bowl stir together the 2 cups all-purpose flour and salt. Using a pastry blender or two knives, cut in the shortening until pieces are pea-size.
Sprinkle 1 tablespoon cold water over part of the mixture; gently toss with a fork. Push moistened dough to sides of bowl. Repeat, using 1 tablespoon cold water at a time, until all of the dough is moistened.
Divide dough in half. Form each half into a ball.
On a lightly floured surface, roll half of the pastry into a 12-inch circle, line a 9-inch pie plate with pastry.
Trim pastry 1/2 inch beyond edge of pie plate. Fold under extra pastry.
Line pastry with double thickness of foil. Bake in a 450 degree F oven for 8 minutes. Remove foil and bake for 5 to 6 minutes more or until golden brown.
Cool on a wire rack. On a lightly floured surface, roll remaining pastry into a 12-inch circle.
Using a 2- to 3-inch cutter, cut pastry into desired shapes(leaves are a nice choice), cover cutouts loosely; set aside.
Meanwhile, in a large saucepan stir together the sugar, cornstarch, and 2 tablespoons flour and stir in rhubarb, raspberries, and apple.
Cook over low heat, stirring frequently, until fruit begins to juice out then increase heat to medium and cook and stir over medium heat until thickened and bubbly.
Transfer to the baked pie shell. Brush edge of pie with milk and place pastry cutouts over fruit filling and around the edge of the pie.
Brush pastry cutouts with milk and, if desired, sprinkle with sugar.
Bake in a 375 degree F oven about 25 minutes or until pastry is golden brown, cool on a wire rack. Makes 8 servings.
For a Double-Crust Pie:
For a conventional pie with a filling that doesn't require precooking, line pie plate with half of the pastry, as directed above, except do not trim pastry or fold under.
Omit the prebaking step.
Set pie plate aside.
Roll out second half of pastry; cover with waxed paper and set aside.
To prepare filling, omit the cornstarch and reduce the raspberries to 1 cup. In a large mixing bowl stir together the sugar and, if using fresh rhubarb, 6 tablespoons of all-purpose flour. (If using frozen rhubarb, increase the all-purpose flour to 1/2 cup.)
Stir in the rhubarb, raspberries, and apple. Transfer filling to the pastry-lined plate.
Trim pastry even with rim of pie plate. Cut slits in top crust; place crust over filling. Fold top crust under bottom crust; flute edge as desired.
Cover edges with foil. Bake in a 375 degree F oven for 25 minutes. Remove foil; bake 20 to 25 minutes more or until top is golden and fruit is tender.
Cool on a wire rack.
Make-Ahead Tip: Bake pie up to 8 hours before serving.