In a large mixing bowl, combine 2 cups of all-purpose flour, 1 tsp salt, 1–2 tbsp sugar, and ⅛ tsp baking powder. Using a pastry cutter, cut in 1 cup of shortening until the mixture resembles coarse crumbs. Gradually add ½ cup of cold water, mixing until a dough forms. Divide the dough in half, shape into discs, wrap in plastic, and refrigerate for at least 30 minutes to firm up.

In a medium bowl, mix together 1 cup of granulated sugar, ⅓ cup ClearJel starch, and a pinch of salt. Gently fold in 5 cups of mixed berries, along with 1 tbsp of orange juice and 1 tbsp of lemon juice, ensuring every berry is evenly coated. Let the filling sit for about 10 minutes.

Preheat your oven to 375°F (190°C). On a lightly floured surface, roll out one disc of the chilled dough into a 12-inch circle. Carefully transfer it to a 9-inch pie pan and pour in the mixed berry filling.

Roll out the second disc of dough, cut it into strips to create a lattice top, or create a fun Halloween-themed design. Lay your lattice over the berry filling, sealing the edges. Brush with an egg wash.

Sprinkle sugar over the lattice top and bake for about 45–50 minutes, or until the crust is golden and the filling bubbles.

Once baked, remove the pie from the oven and let it cool on a wire rack for at least 30 minutes before serving.