In a large bowl, combine the flour, salt, and butter.
Using your fingertips (or a pastry cutter), rub the butter and flour together until it looks like breadcrumbs.
Add the very cold water and use a cold knife to combine. If the dough is too dry, add an additional 1 tbsp of cold water at a time.
Shape the dough into a ball and wrap with plastic wrap. Chill for 30 minutes before using.
On a lightly floured surface, roll the dough out to 1/8 inch thick and larger than your tart pan.
Line the tart pan with the dough, making sure it is flush against the bottom and sides.
Trim the excess dough by taking your rolling pin along the top of the tin.
Use a fork and poke the bottom of the pastry dough repeatedly.
Fill the pastry shell with pie weights (or rice or beans) to prevent the dough from rising while it bakes.
Bake at 350 for 25 minutes or until the pastry shell is a light golden brown.