This recipe comes from Emily Hilliard, whose blog Nothing in the House celebrates all things pie-related. The crust calls for half a beaten egg. Emily sets the other half aside to brush on the top crust, for a golden shine. If you're not baking right away, you can use the whole beaten egg in the dough, and decrease the amount of water by 1 1/2 tablespoons.
In a large mixing bowl, whisk together the flour, sugar, and salt. Using a pastry cutter or two knives, cut in the butter. You want to make sure some chunks of butter about the size of your thumbnail remain intact, as that's what makes the crust flaky.
In a separate small bowl, whisk together half the egg, water, and vinegar, and pour into the flour/butter mixture. Mix until the dough just begins to come together (it should still be a little shaggy). Divide the dough in two pieces and form it into two disks about 1" thick. Wrap tightly and chill for at least an hour before rolling out.
Roll out the pie crust according to the directions in your filling recipe. Store unbaked pie dough, well-wrapped, in the refrigerator for 2 days or in the freezer for up to 2 months.
Need some tips about how to roll out a pie crust? Please read our Complete Guide to Perfect Pie Crust, and our Complete Guide to Pie Baking.
