Instructions

for the pie dough

Whisk ice water and sour cream together in bowl. Process flour and salt in food processor until combined, about 5 seconds. Scatter chilled butter over top and pulse until butter is size of small lentils, about 10 pulses. Drizzle half of sour cream mixture over top and pulse until incorporated, about 3 pulses; repeat with remaining sour cream mixture.
Pinch dough with your fingers; if dough feels dry and does not hold together, add 1 to 2 tablespoons more ice water and pulse until dough forms large clumps and no dry flour remains, 3 to 5 pulses.
Divide dough into 2 even pieces. Form each piece into 4-inch disk, wrap tightly in plastic wrap, and refrigerate for 1 hour. (Before rolling dough out, let it sit on counter to soften slightly, about 10 minutes.)

for the apple-pear filling

Meanwhile, cut vanilla bean in half lengthwise and scrape out seeds using tip of paring knife. Toss apples, pears, Sucanat, lemon zest, salt, cinnamon, and vanilla seeds and bean together in Dutch oven. Cover and cook over medium heat, stirring often, until fruit is tender but still holds its shape, 15 to 20 minutes. Transfer fruit mixture and any juices to rimmed baking sheet and let cool to room temperature, about 30 minutes. Discard vanilla bean.

for the pie

Adjust oven rack to lowest position and heat oven to 425 degrees. Remove 1 disk of dough from refrigerator and roll out between 2 large sheets of parchment paper or plastic wrap to 12-inch circle, about ⅛ inch thick. (If dough becomes soft and/or sticky, return to refrigerator until firm.) Remove parchment from one side of dough and flip onto 9-inch pie plate; peel off second layer of parchment. Working around circumference, ease dough into plate by gently lifting edge of dough with your hand while pressing into plate bottom with your other hand. Leave dough that overhangs plate in place; refrigerate until dough is firm, about 30 minutes.
Meanwhile, roll second disk of dough between 2 large sheets of parchment paper or plastic wrap to 12-inch circle, about ⅛ inch thick. Refrigerate, leaving dough between parchment sheets, until firm, about 30 minutes.
Drain cooled apple mixture in colander set over bowl. Measure out ¼ cup drained juice, discarding extra, and stir in lemon juice.
Spread apple mixture into chilled dough-lined pie plate, mounding fruit slightly in middle, and drizzle with juice mixture. Loosely roll dough circle around rolling pin and gently unroll it onto filling.
Trim any overhanging dough to ½ inch beyond lip of plate, then pinch edges of top and bottom crusts firmly together. Tuck overhang under itself; folded edge should be flush with edge of plate. Crimp dough evenly around edge of plate using your fingers. Cut four 2-inch slits in top of dough and brush surface with beaten egg white.
Set pie on aluminum foil–lined baking sheet and bake until crust is light golden brown, about 25 minutes. Reduce oven temperature to 375 degrees, rotate sheet, and continue to bake until juices are bubbling and crust is deep golden brown, 40 to 50 minutes. Let pie cool on wire rack until juices have thickened, about 2 hours. Serve.