Begin by cubing the butter and chilling it in the refrigerator. In a food processor, pulse together the flour, sugar, and salt until combined. Next, add the chilled butter and process until the mixture resembles coarse crumbs. Gradually drizzle in the ice water, pulsing until the dough just holds together.

Once your dough is formed, divide it into two equal balls. Flatten each ball slightly, wrap them in plastic wrap, and chill in the refrigerator for about 1 hour.

After chilling, let the dough sit at room temperature for 30 minutes. On a lightly floured surface, roll out one ball of dough to fit a greased 9-inch pie dish.

In a large mixing bowl, combine the flour, brown sugar, cinnamon, lemon zest, and salt. Next, slice the strawberries and dice the Granny Smith apple, then toss the fruit in the bowl with the lemon juice and vanilla extract until well coated.

Take the chilled pie crust from the refrigerator and pour the prepared fruit filling evenly into it. Dot the filling with small pieces of butter to enhance flavor. Roll out the second ball of dough for the top crust.

Preheat your oven to 350°F (175°C). Bake the assembled Strawberry Apple Pie in the oven for 45-50 minutes, or until the filling is bubbling and the crust is golden brown.

Once baked, remove the pie from the oven and allow it to cool at room temperature for at least 1 hour.