In medium bowl, mix 1 1/2 cups flour, 1 teaspoon sugar and the salt. Cut in 1/2 cup butter, using pastry blender or fork, until crumbly. Stir in egg yolk with fork. Sprinkle with water, 1 tablespoon at a time, tossing until ball of dough forms. Flatten ball to 1/2-inch thickness. Wrap in plastic wrap; refrigerate 30 minutes.