In a medium bowl, combine flour and salt. This will be the dry mixture for your crust, ensuring that the flavor of the Blueberry Pie is well-rounded from the start.
Add the cold, cubed butter and chilled vegetable shortening to the bowl. Use a pastry cutter to mix the ingredients together until they resemble coarse crumbs. You want to see little bits of fat mixed in with the flour.
Pour in the ice-cold water a little at a time. Mix until the dough just comes together. Be careful not to overwork it; you want to maintain that flaky texture.
Once the dough is formed, separate it into two equal portions. Wrap each portion in plastic wrap and refrigerate for about an hour, or even up to three days. Chilling the dough is essential for achieving the perfect crust.
After chilling, remove one dough ball from the refrigerator. Roll it out on a lightly floured surface into a 13-inch circle. This will be the bottom crust for your Blueberry Pie.
Transfer the rolled-out dough into a 9-inch pie dish, pressing gently to fit. Trim any excess hanging over the edges and place the crust back in the fridge while you prepare the filling.
In a separate medium bowl, mix together the fresh blueberries, lemon zest, lemon juice, ground cinnamon, salt, sugar, and cornstarch. This filling is what makes the pie so delicious, so ensure everything is well combined.
Carefully transfer the blueberry filling to the prepared pie crust in the dish. Make sure to spread it evenly across the crust.
Remove the second ball of dough from the refrigerator and roll it out into a 12-inch circle. Use a knife or pastry wheel to cut this circle into 10 to 12 equal strips. This will create the lattice top for your pie.
Retrieve the bottom crust from the refrigerator, and if necessary, trim any excess dough from the edges using scissors. You can leave about 1 inch of excess dough for a thicker crust.
Arrange the strips of dough over the pie filling in a lattice pattern. Pinch the edges together to seal. For a detailed tutorial on this technique, check out my lattice pie crust post!
To create a beautiful golden top, mix together the egg and water for an egg wash. Brush this mixture over the lattice strips.
Preheat your oven to 425°F/220°C. Bake the pie for about 20 minutes. Then, reduce the heat to 375°F/190°C and continue baking for an additional 30 minutes. The crust should be golden and the filling bubbly.
Allow the pie to cool for at least two hours before serving. This resting time lets the filling set up nicely, so it doesn't run everywhere when you cut into it. Enjoy your delicious Blueberry Pie as is, or with a scoop of vanilla ice cream!