In a very large bowl, stir together the granulated sugar and quick-cooking tapioca; add frozen cherries. Gently toss until coated. Let mixture stand about 45 minutes or until fruit is partially thawed but still icy; stirring occasionally.*
Transfer cherry mixture to a 4-quart Dutch oven. Add 2 tablespoons water. Cook and stir over medium heat until slightly thickened and bubbly. Let cool to room temperature. Cover and chill in the refrigerator while preparing pastry.
Prepare and roll out Single Crust Pie Shell pastry. Line a 9-inch pie plate with pastry. Trim overhang to an even 1 inch all the way around. Tuck the crust under and flute the edges. Do not prick pastry.
In a medium bowl, stir together the oats, flour, brown sugar, salt and cinnamon. Using a pastry blender, cut in butter until mixture resembles coarse crumbs.
Transfer cherry mixture to the pastry-lined pie plate. Sprinkle crumb topping over cherry mixture. To prevent overbrowning, loosely cover pie with foil.
Place pie plate on middle shelf in oven; place foil-lined baking sheet on lower rack beneath pie. Bake in a 350 degrees F oven for 20 minutes. Remove foil. Bake 40 to 45 minutes more or until filling is bubbly and crumb topping is golden brown. Cool on a wire rack at least 2 hours before serving. Makes 8 servings.
it isn't necessary to let mixture stand 45 minutes.
In a medium bowl, stir together cake flour, all-purpose flour, and salt. Using a pastry blender, cut in butter and shortening until pieces are pea-size.
In a small bowl, stir together 4 tablespoons of the water, egg, and lemon juice. Using a large fork, gently toss the flour mixture and egg mixture together. If there are any dry parts, add the remaining 1 tablespoon of water and gently toss to moisten evenly (should be a mass of very large crumbs).
Turn crumb mixture out onto a lightly floured surface. Using your fingers, gently form a ball. Using just a bit of flour, knead 4 to 5 times to form a ball. Using your hands, flatten into a disc about 1 inch thick. If necessary, wrap the dough in plastic wrap and chill in the refrigerator for 1 to 2 hours or until easy to handle.
On a lightly floured surface, roll dough from center to edges into a circle 12 inches in diameter. To transfer pastry, wrap it around the rolling pin. Unroll pastry into a 9-inch pie plate. Ease pastry into pie plate without stretching it and gently fit pastry into dish.
Trim the overhang to an even 1 inch all the way around. Tuck the crust under and flute the edges. Bake as directed in individual recipes. Makes 1 pie crust