Place the flour, salt, and sugar in the bowl of a food processor fit with a metal blade and pulse to combine.

Add the buttery sticks and pulse until the mixture resembles a coarse meal. (There should be pieces of margarine the size of peas and some slightly large pieces as well). Add the egg yolk and process until the egg yolk is combined and the dough just starts to come together.

Transfer the dough to a bowl. If you can press it into a smooth ball do not add any water. If the dough is still crumbly add the water 1/2 tablespoon at a time until it you can press it into a smooth ball.

Place the dough on a piece of plastic wrap and flatten the dough into a disk one inch thick. Wrap well and refrigerate for one hour. (If you are in a real hurry you can freeze it for 15 minutes.) The dough can be kept refrigerated for up to five days or frozen, well wrapped, for up to a month.

When you are ready to use the dough remove it from the refrigerator and transfer it to a lightly floured piece of parchment paper. Top with an additional sheet of parchment and roll out to 1/4 inch thick. Peel off the top piece of parchment place the pie pan upside down over the circle of dough and invert the pan and parchment with dough. Peel off parchment and settle the dough into the pan. (If it cracks a bit just use your fingers to press the dough back together. You can also use extra dough to patch holes if necessary.) Trim the edges and bake and fill according to the recipe instructions for the pie you are making.