In a small bowl, mix flour and salt; cut in shortening until crumbly. Gradually add half the ice water and vodka, tossing with a fork until dough holds together when pressed. Add more if needed. Shape into a disk; wrap in plastic. Refrigerate 1 hour or overnight., Preheat oven to 425degrees. On a lightly floured surface, roll dough to a 1/8-in.-thick circle; transfer to a 9-in. pie plate. Trim pastry to 1/2 in. beyond rim of plate; flute edge. In a small bowl, whisk egg with water. Brush over pastry; refrigerate until ready to fill., Meanwhile, beat together filling ingredients until blended; transfer to crust. Bake on a lower oven rack 15 minutes. Reduce oven setting to 350degrees; bake until a knife inserted in the center comes out clean, 35-40 minutes longer. (Cover edges with foil during the last 15 minutes to prevent overbrowning if necessary.) Cool completely on a wire rack. Store in the refrigerator.