Preheat oven to 400.
MIX flour, sugar, and salt in a large bowl; add butter. Blend in a mixer until dough forms into pea-sizes balls
Drip in water, stir, then drip in more, until dough holds loosely together, and you can roll dough into a ball. Flatten into a 4 in round disk and refrigerate. After 30+ minutes remove it from the fridge and allow to soften until malleable but still cold. On a lightly floured surface, roll into a 12-inch circle about 1/8 inch thick.
Place dough in a 9-inch round tart pan.