1. Make the Pie Crust: In a large bowl, whisk together 1 ¼ cups all-purpose flour and ½ teaspoon salt. Cut in the ½ cup very cold, cubed butter using a pastry blender or your fingertips until pea-sized crumbs form. Gradually add ice water, 1 tablespoon at a time, mixing until the dough just comes together. Do not overmix. Form the dough into a disk, wrap it tightly in plastic wrap, and chill for at least 30 minutes in the refrigerator.
2. Prepare Pie Plate: On a lightly floured surface, roll out the chilled pie dough into a 12-inch circle. Carefully transfer the dough to a 9-inch pie plate, trimming the edges and crimping them as desired. Prick the bottom of the crust several times with a fork. Place the prepared pie plate in the refrigerator while you prepare the filling.
3. Prepare the Filling: In a large bowl, gently combine the chopped rhubarb, sliced strawberries, ¾ cup granulated sugar, ¼ cup cornstarch, 1 tablespoon lemon juice, 1 teaspoon vanilla extract, and a pinch of salt. Mix until the fruit is evenly coated with the sugar and thickener. Set aside.
4. Make the Crumb Topping: In a medium bowl, whisk together ½ cup all-purpose flour, ¼ cup granulated sugar, ¼ cup packed light brown sugar, and ½ teaspoon ground cinnamon. Cut in the ¼ cup very cold, cubed butter using a pastry blender or your fingertips until coarse, crumbly pieces form. Set aside.
5. Assemble the Pie: Pour the prepared fruit filling into the chilled pie crust. Evenly sprinkle the crumb topping over the fruit filling, covering it completely.
6. Bake the Pie: Preheat your oven to 400°F (200°C). Place the pie on a baking sheet (this will catch any potential drips from the bubbling filling). Bake for 20 minutes at 400°F. Then, reduce the oven temperature to 375°F (190°C) and continue baking for another 35-45 minutes, or until the crumb topping is golden brown and the filling is visibly bubbling thickly. If the pie crust edges or crumb topping start to brown too quickly, loosely tent the pie with aluminum foil.
7. Cool Completely: Carefully transfer the baked pie to a wire rack and let it cool completely for at least 3-4 hours (or ideally overnight) before slicing and serving. This cooling time is absolutely crucial for the filling to set properly and prevent a runny pie.
Notes
For the best flavor and texture, use firm, ripe rhubarb and sweet, juicy strawberries. The sweetness of the fruit can vary, so taste a piece of strawberry before adding all the sugar to the filling; you might adjust slightly. Cooling the pie completely is essential for the filling to set; patience will be rewarded! Store any leftover pie at room temperature for up to 2 days, or covered in the refrigerator for up to 4 days. This pie is delicious on its own, or served warm with a scoop of vanilla bean ice cream or a dollop of fresh whipped cream.
Keyword Baking, Crumb Topping, Dessert, fruit pie, Pie, strawberry rhubarb pie