12 tablespoons cold Unsalted butter cut into chunks
2 large egg yolk (reserve the whites)
5 to 6 teaspoons ice water
2 cups raspberries
2 cups blackberries
4 tbs sugar
3 tsp cornstarch or flour
Instructions
In a food processor, mix flour and salt. Add butter and pulse until mixture resembles a coarse meal. Add egg yolks and water one spoon at a time; processing just until dough begins to form a ball. Form dough into a disk and wrap in plastic wrap. Let dough rest in refrigerator for 15 to 20 minutes.
While the dough is resting, turn the oven on and preheat to 375 degrees (350 if your oven tend to be too hot).
Line a baking sheet with parchment paper. Set one piece of plastic wrap on a work surface. Lightly dust it with flour. Set dough in center of plastic wrap sheet. Lightly dust dough surface with flour and cover with another piece of plastic wrap. With a rolling pin, roll dough evenly into a 14 inch disk.
Peel off top sheet of wrap and invert dough into lined baking sheet. Remove remaining plastic wrap. In a small bowl, Mix sugar and cornstarch. Sprinkle center of dough with two tablespoons of cornstarch mixture – this will form a seal and prevent crust from getting soggy during baking. Distribute berries in center of pastry. In a bowl, Sprinkle remaining cornstarch mixture over berries. Gently fold edges over berries pleating to fit. Leave an opening of about six inches wide in center. Brush pastry with reserved egg whites and sprinkle with sugar.
Bake tart at 375 until crust is golden and juices in center bubble. Cool in pan for 20 minutes before serving.
Notes
**Note: Do not use frozen berries. They will release too much liquid which will result in a very soggy crust.
Recipe by Fraiche Pantry at https://www.fraichepantry.com/2014/02/06/french-rustic-berry-tart/