Pulse the flour, sugar, salt and lemon zest in a food processor workbowl until combined.
Add the butter and process until the butter forms pea-sized pieces (this will take just a few seconds). A few visible chunks of butter in the dough are fine — they create flaky air pockets while the pastry bakes.Add the ice water and lemon juice and pulse until the dough just begins to come together, but not so much that if forms a ball (that will toughen the dough) Add more water if it looks dry, one teaspoon at a time.
Dump the dough onto a floured counter or work surface. Knead the dough into a smooth ball, then cut into 2 equal pieces. Flatten each piece into a flat disc. Wrap each disc in plastic wrap and refrigerate 1 hour or up to 1 day before using.
Rolling out the dough
Smack one package of dough with a rolling pin to flatten. Unwrap and put the dough on a large floured counter. Sprinkle the top of the dough with more flour and roll the dough firmly away from you, turning the paper after each roll to create a circle about 2 inches larger than your pie dish (12-inches for a 9-inch pie). Sprinkle lightly with more flour if you notice the dough starting to stick.
Pie Crust without a food processor:
In a large bowl, stir together the flour, sugar, salt and zest. Cut the butter into the flour with a pastry blender or a fork until the butter pieces are the size of large peas. Make a well in the center of the flour mix and add the water and lemon juice.
Blend with a fork until the dough starts to come together. If there's flour on the bottom of the bowl, add more water a teaspoon at a time until you can gather the dough into a ball.
Notes
If the dough is very firm after chilling, leave at room temperature until it feels pliable.
The key to great, flaky pie crust is starting with cold ingredients - especially the butter and water. One trick is cut the butter and place in the freezer for 15 minutes before mixing the dough. To make ice water, fill a liquid measuring cup with ice cubes, then fill with water. Let sit 5 minutes before measuring and making the dough (don't use the ice, though).
Pie crust dough can be frozen for 3 months. Wrap securely in 2 layers of plastic wrap, then place the package in a zip-tip freezer bag.