Basic Pie and Tart Dough

There are three ways to make this basic dough: by hand, in a food processor, and in a stand mixer fitted with the paddle attachment. The key to success in every case is to keep the butter cold and not to overwork the dough. If you are using a food processor, the butter will be very finely chopped into the dough, but if you are making the dough by hand or in a mixer, you will probably see butter chunks dispersed throughout the dough. Resist the compulsion to work in every little piece of but