In the bowl of a food processor fitted with the blade attachment, pulse together the flour, sugar, salt, butter and shortening until the mixture resembles cornmeal but there are still pea-sized chunks of fat.
In a small bowl, stir together the ice water and lemon juice. Slowly add the liquid to the flour mixture, pulsing, until the dough just comes together. Squeeze a small piece of dough between your thumb and index finger to make sure it holds its shape.
Turn the dough out onto a lightly floured surface and divide it in half. Gently turn over each piece of dough a few times so that any dry bits are incorporated. Form each piece into a loose disk, cover the dough with plastic wrap and let it rest in the refrigerator for at least 20 minutes.
Adapted from "Pie It Forward: Pies, Tarts, Tortes, Galettes, and Other Pastries Reinvented" by Gesine Bullock-Prado © Harry N. Abrams; 1st Printing edition 2012. Provided courtesy of Gesine Bullock-Prado. All rights reserved.