This recipe is originally from the America’s Test Kitchen cookbook. It makes a pretty and tasty summer dessert. You can use any mix of fresh berries and/or stone fruit that you like. Serve with vanilla ice cream or whipped cream.
7 teaspoons unsalted butter, cut into 1/2 inch pieces- and chilled
For the dough: Stir the sour cream and water together in a small liquid measuring cup and refrigerate until needed. Mix the flour, cornmeal, sugar, and salt in a food processor. Scatter half the butter over the top and process using short pulses until the butter is the size of small peas, about 4 pulses. Scatter the remaining butter over the flour and continue to pulse until most of the butter is incorporated yet some pea sized bits remain, about 4-8 pulses. Continue to pulse while pouring the sour cream mixture through the feed tube (continued on next page) until the dough just comes together around the blade, about 5 pulses. Turn the dough onto a sheet of plastic wrap and press into a 6 inch disk. Wrap tightly in plastic wrap and refrigerate at least 1 hour.*
Preheat the oven to 400 degrees with the rack in the middle position. Roll the chilled dough between 2 large sheets of parchment paper into a 13 inch round. Slide the dough (still between the paper) onto a baking sheet and refrigerate 20 minutes until firm.
For the filling: Discard the top sheet of parchment and pile the fruit in the center of the dough, leaving a 2-3 inch border. Sprinkle 1-2 tablespoons of the sugar over the fruit and dot with the butter.
Fold the edges of the dough over the fruit. (Loosen with a thin bladed knife if the dough sticks to the paper). Brush the top of the tart with water and sprinkle with the remaining 1 tablespoon sugar.
Bake until the crust is golden brown and crisp and the fruit is bubbling, about 40 minutes. Transfer the baking sheet to a wire rack and let the tart cool for 10 minutes. Slide the tart off the baking sheet and cool on the rack until warm or room temperature before serving.
*If you like, you can keep the dough, wrapped tightly in plastic wrap, for up to 2 days in the refrigerator or up to 2 months in the freezer. Let dough thaw and soften until malleable before attempting to roll it out.