Mix the flour, sugar and salt; rub in the butter until the mixture resembles coarse breadcrumbs. Stir in 1 teaspoon of water with a fork until the mixture forms a ball. Roll out between two pieces of parchment paper. Press gently into a tart pan. Prick crust with a fork to prevent bubbling. Bake for 20 minutes at 350, or until a light golden brown.