• Preheat oven to 400 degrees F.
• Shape the pie dough into a 9-inch pie pan, then par-bake with pie weights (or alternatives as listed above) for 10 minutes. Remove and set aside.

Make the filling

• Add the cranberries, strawberries, 1 cup sugar, orange zest, salt, and cornstarch in a medium saucepan. Simmer over medium heat for 10 minutes until the filling has softened and is jammy. Remove from heat and let cool for 10 minutes while you make the crumble topping.

Make the streusel topping

• In a bowl, combine together the oats, flour, remaining 1/3 cup sugar, brown sugar, and cinnamon together. Drizzle with melted butter, then work into the mixture with a spoon or your hands.
• Reduce the temperature to 350 degrees F after parbaking the crust.
• Add cranberry filling to the pie crust, then sprinkle the streusel topping over the cranberry filling. Bake pie for 45 to 50 minutes,- until juices are bubbling enough that they splash a bit onto the crumb topping. If the pie browns too quickly, cover the top with a piece of foil for the remaining baking time. Transfer to a wire rack to cool a bit before serving. If desired, sprinkle with powdered sugar before serving.