Blueberry-Blackberry Rustic Tart Recipe

In a large bowl, mix flour, sugar and cornmeal; cut in butter until crumbly. Gradually add buttermilk, tossing with a fork until dough holds together when pressed. Shape into a disk; wrap in plastic wrap. Refrigerate 30 minutes or overnight. Preheat oven to 375 °. On a lightly floured surface, roll dough into a 14-in. circle. Transfer to a parchment paper-lined baking sheet. In a large bowl, combine berries, sugar, flour and lemon juice; spoon over pastry to within 2 in. of edges. Fold pastry edge over filling, leaving center uncovered. Brush folded pastry with beaten egg; sprinkle with turbinado sugar. Bake 55-60 minutes or until crust is golden brown and filling is bubbly. Using parchment paper, slide tart onto a wire rack to cool. If desired, serve with whipped cream.