Preheat your oven to 400 degrees F.

In a large bowl, mix together the berries, sugar, cornstarch, vanilla extract, and lemon juice. Set aside.

Roll out your pie dough to a 1/8-inch thickness. Cut in sections, making sure you have enough dough to fill 5-6 mini pie dishes plus 5-6 additional pieces to top each pie.

Fill each dish with the pie dough, allowing any excess dough to hang over the edge. Then, evenly fill each with the prepared mixed berry filling.

Brush the lip of the pie dough on the dishes with an egg wash and then top with the remaining pie dough pieces. Pinch or use a fork to seal. Trim off any excess dough around the sides of the dish.

Use a knife to cut two vents into the top of the dough. Brush with the egg wash and sprinkle with coarse sugar.

Set the pot pies on a baking sheet and place the sheet in the oven. Then, reduce the oven temperature to 350 degrees F. Bake for 35-40 minutes or until the tops are lightly browned and the filling is bubbly.

Allow the pies to cool for at least 30 minutes before serving.