Heat oven to 400°F.
Rub zest into sugar in bowl.
Whisk in cornstarch/salt.
Stir in berries/vanilla.
Whisk dry ingredients for crust in bowl.
Pour in butter/milk; stir with fork.
Knead dough.
Turn dough onto parchment paper; shape in flat disc cover with parchment paper.
Roll out until about ¼-inch thick.
Place dough on baking sheet; peel off top sheet.
Transfer berries to center of dough.
Fold up edges, Brush with milk; sprinkle with turbinado sugar.
Bake 45 mins.
