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To make the crust: Whisk together the flour, sugar, and salt.
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Add the cold cubed butter. Using your fingers, work the butter into the flour mixture until it's unevenly crumbly. Some butter pieces will be the size of oat flakes; some will be the size of peas.
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Whisk together the cold buttermilk and egg yolk. Create a well in the center of the butter and flour mixture and pour in the buttermilk mixture. Use a spatula to gently work the wet ingredients into the dry. The mixture will be rather shaggy; just make sure that most of the dry ingredients are kissed by the liquid, if not totally moistened.
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Dump the shaggy dough onto a clean work surface and use the sides of your hands to gently but firmly coax and squeeze the dough into a rough disk. If you find that the dough is just too dry and not coming together, add another tablespoon of buttermilk.
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Knead the dough until it's cohesive (cracks will still be present; that's OK) and divide it in half. Wrap each disk in plastic wrap and refrigerate for at least 1 hour.
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While the crust is chilling, place a rack in the center of the oven and preheat the oven to 400°F. Line a baking sheet with parchment paper.
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To make the filling: Toss together the strawberries, as many lemon slices as you'd like, lemon juice, ginger, sugars, cornstarch, salt, and spices. Toss until all of the cornstarch has disappeared into the strawberries. Let the mixture rest for 10 minutes; the strawberries will begin to produce juice.
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To assemble the pie: Generously flour a clean counter. Unwrap one piece of the dough and lightly flour the top. Roll it into a circle 1/8" thick and about 12" in diameter. Transfer it to a 9" pie pan.
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Spoon the filling into the crust.
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Roll the remaining piece of dough into a 12" circle. Cut it into 1" strips, and use the strips to weave a lattice crust.
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Brush the egg wash over the crust, then sprinkle with granulated or coarse white sparkling sugar.
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Place the pie on the prepared baking sheet and bake for 15 minutes. Reduce the heat to 350°F and bake the pie for an additional 40 to 50 minutes, or until the crust is golden and the filling is bubbling.
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Remove the pie from the oven and allow it to cool completely before serving.