Place flour, salt and sugar (if using) in the bowl of a food processor. Add cubed butter on top. Turn on food processor and let it run just until the butter disappears. STOP!
Add water and pulse until the dough begins to clump together. Don't keep pulsing and whirring until it turns into a ball in the food processor.
Turn the dough out into a large bowl. Gently work it into a ball. If it's too dry and not holding together, lightly sprinkle with some ice water and work it in..
Divide the ball of dough in half.
If you're making two pies, roll out each piece to 12 inches in diameter. Place them in 9-inch pie plates. Trim the dough and crimp the edges. Cover lightly with plastic wrap and place in the refrigerator for at least 30 minutes before using.
For a double-crust pie, wrap one ball of dough in plastic wrap and place in the refrigerator. Roll out the second half to 12 inches and place in a 9 inch pie plate. Trim the overhang, lightly cover the pie crust with plastic wrap and place in the refrigerator for at least 30 minutes before baking.
When ready to use the double-crust, remove both ball of dough and pie plate. Add filling to pie plate. Roll out remaining dough to 11 inches. Fold in quarters and transfer to pie plate. Unfold and spread over filling. Trim the overhang to one inch. Fold overhang under bottom crust and crimp. Cut vents in top crust and bake pie according to directions. If the edges of the crust start to darken before the pie is ready, cover with aluminum foil.