In a medium bowl, whisk together the flour, sugar and salt. With a pastry blender or fork, cut in the cubed butter until it resembles coarse crumbs about the size of a pea, about 4 minutes. Spoon the cold water over the crumbs, stirring in only about 1 tbsp at a time, until the dough begins to come together. It may be a bit crumbly, so it will have to be kneaded with your hands. Try to touch it as little as possible to prevent the butter from melting. When most of the dryness is gone and the dough holds together on its own, it is ready.