2. In a mixing bowl, combine flour and salt. Cut in butter until mixture resembles coarse crumbs. Gradually add ice water, tossing with a fork until dough forms a ball. Divide dough in half. Shape each into a disk; wrap and refrigerate for 1 hour or overnight.
3. On a lightly floured surface, roll out one half of the dough to fit a 9-inch pie dish. Transfer dough to pie dish. Trim even with edge. Add filling.
4. For filling, in a large bowl, combine blueberries, sugar, cornstarch, lemon juice, lemon zest, and vanilla extract. Toss to coat. Spoon into crust.
5. Roll out remaining dough to fit top of pie; place over filling. Trim, seal, and flute edges. Cut slits in top. Brush with egg wash.
6. Bake for 50 minutes or until crust is golden brown and filling is bubbly. Cool on a wire rack.
Notes:
Let the pie cool completely before slicing to ensure the filling sets properly.