Combine all-purpose flour, salt and sugar in a bowl.
Cut butter into the flour mixture using pastry blender, 2 dinner knives or your fingers until mixture resembles coarse crumbs.
Add cold water, a tablespoon at a time, mix using a pastry knife or dinner knife or fork.
Form mixture into a ball and flatten into a disc.
Put in the fridge to rest for half an hour. (You can make this ahead of time, a day in advance or the night before.)
When ready to make pie, take dough out of the fridge and let it soften a little, about 10-15 mins before rolling.
Roll dough flat using a rolling pin about 10 inches in diameter.
Transfer to a 9-inch pie plate.
Crimp the edges.