Raspberry Rhubarb Crostata

For the pastry, place the flour, granulated sugar, and ¹⁄₂ tsp salt in the bowl of a food processor fitted with the steel blade. Pulse a few times to combine. Add the butter and toss carefully with your fingers to coat each cube of butter with the flour. Pulse 12 to 15 times, or until the butter is the size of peas. With the motor running, add ¹⁄₄ cup of ice water all at once through the feed tube. Keep hitting the pulse button just until the dough comes together. Turn onto a well-floured board, cut in half and form into two disks. Wrap and refrigerate for at least an hour. (Wrap the second dough well and freeze if not using.) If the dough is refrigerated for more than 1 hour, let it rest at room temperature for 15 minutes before working with it.

For the filling, place 3 tbl of water in small bowl, whisk in the cornstarch, and set aside. In a large heavy-bottomed saucepan, combine the rhubarb, raspberries, granulated sugar, orange zest, and orange juice. Cook over medium heat for 5 to 6 minutes, until some of the juices are released. Stir in the cornstarch, bring to a boil, lower the heat, and simmer for 2 minutes. Refrigerate for 30 minutes, until cool.

Preheat the oven to 425 degrees. Line a sheet pan with parchment paper.

Roll the pastry into an 11 to 12 inch circle on a lightly floured surface and transfer to the prepared pan. Pile the raspberry rhubarb mixture onto the pastry, leaving a 1 ¹⁄₂-inch border all around. Fold the border up over the filling, pleating if necessary and pressing lightly. Brush the pastry with egg wash, sprinkle just the pastry with the raw sugar and bake for 30 to 35 minutes, until the pastry is browned and the filling is thickened. Cool for 30 minutes and seve warm or at room temrpatrue.