BLACKBERRY-RASPBERRY HAND PIES

Steps:

• Whisk together sour cream, lemon juice, and ice water in a bowl. Mix together flour, 1/2 teaspoon salt, and 1 teaspoon granulated sugar in a large bowl. Add butter and beat with a mixer on medium-low until mixture resembles coarse meal with some blueberry-size clumps remaining. Gradually beat in sour-cream mixture until just combined but still crumbly. (Squeeze a small amount of dough to see if it holds together. Beat in more water, 1 teaspoon at a time, if necessary.) Divide dough in half, gather into 2 flat rectangles, and wrap in plastic wrap. Refrigerate until just firm, 45 minutes.
• Roll out each rectangle of dough into a 7-by-14-inch rectangle on a piece of floured parchment with a floured rolling pin. (Dough will be very thin.) Transfer rectangles on parchment to 2 baking sheets and refrigerate until firm, 15 minutes.
• Meanwhile, stir together berries, remaining 1/3 cup granulated sugar, cornstarch, and 1/4 teaspoon salt in a bowl. Slide 1 dough rectangle, still on parchment, onto a work surface. With a long side facing you, cut dough crosswise into four 3 1/2-by-7-inch strips.
• Mound 2 tablespoons berry mixture in center of bottom half of each strip. Brush edges with egg wash and fold top half over fruit to enclose. Press firmly to seal and trim bottom edge, leaving folded top edge uncut. Cut vents in each pie and place about 2 inches apart on baking sheet lined with fresh parchment. Transfer to freezer. Repeat with remaining dough and berry mixture. Freeze hand pies until very firm, at least 45 minutes.
• Preheat oven to 375 degrees with racks in upper and lower thirds. Lightly brush pies with egg wash and sprinkle with sanding sugar. Bake, rotating sheets and switching racks halfway through, until pies are golden brown, 35 to 40 minutes. Transfer to a wire rack to cool. Serve warm or at room temperature.