In a food processor combine the flour, sugar, and salt. Pulse once for a few seconds. Add the butter and pulse several times until mixture resembles coarse meal. In a small bowl, mix the yolk and the water and while it is running, add the mixture to the food processor. Pulse the machine until the dough comes together. Remove the dough onto the counter and smear with the palm of your hand several times. Gather the dough up and form a disk. Wrap in plastic and refrigerate for one hour before using.