Make the crust: In a medium-sized bowl, combine the flours, sugar, and salt, and whisk to combine. Add the cold cubed butter. Using your clean fingers, or a pastry cutter, smoosh the cubes of butter into the flour, coating each cube with flour. Add the ice water, and stir gently to combine, until the dough just starts to come together, but you should still see pea-sized pieces of butter. Dump half of the dough out onto a large piece of plastic wrap, and use the plastic to push the dough together into a ball. Wrap tightly, and refrigerate for 30 minutes. Repeat with the second ball of dough.

In a large bowl, combine the blueberries, sugar, cornstarch, lime juice, about 3/4 of the lime zest, vanilla extract, and kosher salt. Stir until the berries are well coated with the cornstarch. Set aside.

Preheat oven to 400 degrees F. Roll out 1 ball of dough on a floured surface with a floured rolling pin, to 1/4" thickness. Use a small plate as your guide, and cut out three 6" circles. Transfer the dough to a rimmed baking sheet, lined with parchment paper. Place about 1/2 c of the blueberry filling (make sure to leave any extra juices in the bowl, otherwise your crust will get soggy) in the center of each circle. With your fingers, crimp the edges of the crust up around the filling. Brush the beaten egg around the edges, and sprinkle with the turbinado sugar. Place the whole pan in the freezer for 15 minutes to firm up the crust. Repeat with the second ball of dough.

Bake for about 30 minutes, or until the crust is very golden brown. Allow to cool to room temperature. Top with vanilla ice cream or homemade whipped cream.