2 1/2 cups all-purpose flour
1 teaspoon table salt
2 tablespoons sugar
12 tablespoons cold unsalted butter cut into 1/4 inch slices
1/2 cup cold vegetable shortening, cut into 4 pieces
1/4 cup cold vodka
1/4 cup cold ice water
6 cups fresh blueberries
1 Granny Smith apple, peeled and grated
2 teaspoons grated zest and 2 teaspoons juice from 1 lemon
3/4 cup sugar
2 tablespoons instant tapioca ground in spice grinder
Pinch table salt
2 tablespoons unsalted butter, cut into 1/4-inch pieces
1 large egg, lightly beaten plus 1 teaspoon water
Process 1 1/2 cups flour, salt, and sugar in food processor until combined. Add butter and shortening and process until the dough just starts to collect in uneven clumps, the dough will resemble cottage cheese curds and there should be no uncoated flour. Scrape the bowl and redistribute dough evenly around processor blade. Add the remaining cup flour and pulse until the mixture is evenly distributed around bowl and mass of dough has been broken up, 4 to 6 pulses. Empty the mixture into a medium bowl.
Sprinkle the vodka and water over the mixture. Use a folding motion to mix, pressing
down on dough until dough is slightly tacky and sticks together. Divide the dough into 2 even balls and flatten each into 4-inch disk. Wrap each in plastic wrap and refrigerate at least 45 minutes or up to 2 days.
Remove the first disk of dough from refrigerator and roll out on generously floured surface. Roll the dough loosely around rolling pin and unroll into pie plate, leaving at least l-inch overhang. Refrigerate while you prepare the filling and until dough is firm, 30 minutes.
Adjust oven rack to lowest position and place a rimmed baking sheet on the oven rack. Heat oven to 400 degrees.
Place 3 cups of blueberries in medium saucepan and set over medium heat. Using potato masher, mash berries several times to release juices. Continue to cook, stirring frequently and mashing occasionally, until about half of berries have broken down and mixture is reduced to 1 1/2 cups, about 8 minutes. Let cool slightly.
Place grated apple in clean kitchen towel or chessecloth and wring dry. Transfer the apple to a large bowl. Add cooked berries, remaining 3 cups uncooked berries, lemon zest, juice, sugar, tapioca, and salt, toss to combine.
Transfer the mixture to dough in the pie plate and scatter butter pieces over filling.
Roll out second disk of dough on generously floured surface. With a 1/4 inch round biscuit cutter, cut a round in the center of the dough, then cut 4-5 more in a circle 2″ away from the first round.
Trim bottom layer of overhanging dough, leaving 1/2 inch overhang. Fold dough under itself so that edge of fold is flush with outer rim of pie plate. Flute edges using thumb and forefinger or press with fork to seal. Brush top and edges of pie with the egg mixture. If dough is very soft, chill the pie in freezer for 10 minutes.
Place pie on the heated baking sheet and bake for 30 minutes. Reduce oven temperature to 350 degrees and continue to bake until juices bubble and crust is deep golden brown, 30 to 40 minutes longer. Transfer pie to wire rack and cool to room temperature.