Preheat the Oven: Preheat your oven to 375°F (190°C).
Prepare the Filling: In a large bowl, gently toss the mixed berries with sugar, cornstarch, lemon juice, vanilla extract, and salt until well combined.
Let the mixture sit for about 10 minutes to allow the berries to release their juices.
Assemble the Pie: Pour the berry filling into the unbaked pie crust, spreading it evenly.
Bake: Bake in the preheated oven for 30-35 minutes, or until the filling is bubbly and the crust is golden brown.
Cool and Serve: Allow the pie to cool for at least 15 minutes before slicing. Serve warm or at room temperature, optionally topped with whipped cream or vanilla ice cream.
Enjoy this refreshing and colorful berry medley pie, perfect for summer gatherings!