Combine the flour, salt, and sugar (if using) in a medium size mixing bowl.
Cut or grate the very cold butter into small pieces and add to the flour mixture. If grating or using a fork instead of a pastry cutter, I suggest cutting the butter into very small pieces and freezing grated butter for at least 10 minutes before using.
Using a fork or pastry cutter, work through the flour and butter mixture to combine the two until small pebbles are formed and most of the flour has mixed with the butter.
Add 3 Tables of very cold water and mix with a fork just until combined. Add 1-2 Tablespoons of very cold water and mix. Continue adding 1 Tablespoon at a time of cold water and mixing gently until the butter and flour starts for form larger pieces. The amount of water you need will vary depending on humidity and other factors, but try not to add too much.
When you can squeeze some of the pie dough in your hands and it holds its shape without crumbling, you have added enough water. The dough should look crumbly at this point.
I like to dump the crumbly dough out onto a large piece of plastic wrap and fold the plastic wrap up to cover the dough completely and then form a disc. If the dough is too crumbly, add another Tablespoon of cold water. Once the dough holds together, split it into two disc of equal size. Weighing the dough is the best way to ensure each pie crust is equal. Wrap each disc in plastic wrap and refrigerate for 15-30 minutes before rolling it out and forming your pie crust.