In a mixing bowl, combine flour, sugar, and salt. Add cold cubes of butter and mix with a pastry cutter or fork until it resembles coarse crumbs.
Gradually add ice water, a tablespoon at a time, until the dough holds together. Divide the dough in half, shape into discs, and refrigerate for at least 30 minutes.
Preheat your oven to 425°F (220°C).
In a saucepan, combine strawberries, rhubarb, sugar, cornstarch, lemon juice, vanilla extract, and cinnamon. Cook over medium heat until the mixture thickens and bubbles, about 5-7 minutes. Remove from heat and let cool.
Roll out one disc of pie dough into a 12-inch circle and place it into the pie dish. Spoon the filling evenly into the crust.
Roll out the second disc of dough and place it over the filling. Trim the edges and crimp to seal. Cut a few slits in the top crust to allow steam to escape.
Bake in the preheated oven for about 45 minutes, or until the crust is golden brown and the filling is bubbly. Check the edges; if they brown too quickly, cover them with foil.
Once done, remove from the oven and let it cool for at least 30 minutes before serving to allow the filling to set.
Serve warm or at room temperature, ideally with a scoop of vanilla ice cream or whipped cream.