Adapted from A Couple in The Kitchen
Pastry for single pie crust (or refrigerated pie crust)
1/2 cup sugar
1/4 cup cornstarch
1 tablespoon balsamic vinegar
1 pint blackberries
1 pint raspberries
1 pint strawberries, hulled and chopped
Powdered sugar and mint for garnishing, optional
Vanilla ice cream or whipped cream for serving, optional
Preheat oven to 425º. Press pie crust into bottom and sides of pie plate. Line the crust with foil and fill with pie weights. Bake for 15 minutes. Remove from oven, remove weights and foil, and set aside.
Reduce oven to 350º. Combine sugar, corn starch, balsamic vinegar and berries in a bowl, tossing until berries are well coated. Pour berry mixture into crust and return pie to oven. Bake for 30 minutes. Allow to cool then garnish as desired.