Pastry (makes enough for 2 crostatas)
2 cups all-purpose flour
1/4 cup granulated sugar
1/2 teaspoon kosher salt
1/2 pound (2 sticks) very cold unsalted butter, 1/2-inch-diced
1/4 cup ice water
1/4 cup cornstarch
1 1/4 pounds rhubarb, cut crosswise into 1/2-inch-thick slices (about 4 cups)
6 ounces raspberries
2/3 cup granulated sugar
1/4 cup freshly squeezed orange juice
1 teaspoon grated orange zest
1 extra-large egg beaten with 1 tablespoon water, for egg wash
Turbinado or demerara sugar, such as Sugar in the Raw
Make the pastry: place the flour, granulated sugar, and salt in the bowl of a food processor fitted with a 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 the ice water all at once through the feed tube. Keep hitting the pulse button just until the dough comes together. Turn the dough out onto a well-floured board, cut in half, and form into 2 disks. Wrap and refrigerate for at least an hour. (Wrap the second dough well and freeze, if not using.)
Make the filling: place 3 tablespoons 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 juice, and orange zest. 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°F. 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 turbinado sugar, and bake for 30 to 35 minutes, until the pastry is browned and the filling is thickened. Cool for 30 minutes and serve warm or at room temperature.
Note: if the dough is refrigerated for more than an hour, let it rest at room temperature for 15 minutes before rolling it out.
Formulation courtesy of Ina Garten's 'Cooking for Jeffrey'. Image courtesy of Quentin Bacon. Published by Clarkson Potter/Publishers, an imprint of Penguin Random House, LLC.