In a food processor, combine all-purpose flour, salt, sugar, and optional ground cinnamon. Add cold unsalted butter and cold shortening, then pulse until the mixture resembles coarse crumbs.

Gradually add cold water, one tablespoon at a time, until the dough clumps together without becoming sticky.

Divide the dough into two balls and wrap each in plastic wrap. Refrigerate for at least 3 hours, or overnight.

On a lightly floured surface, roll one dough ball into a circle, about 1/8 inch thick, and fit it into a 9-inch pie plate.

Preheat your oven to 400°F (200°C). Pour cooled strawberry filling into the bottom crust, then create a decorative lattice pattern using the top crust.

Brush the lattice crust with an egg wash and sprinkle a little sugar over the top. Bake for 20 minutes, then reduce temperature to 350°F (175°C) and bake for an additional 30-40 minutes.

Let the pie cool on a wire rack for at least 1 hour, then refrigerate for an additional 2-3 hours before serving.