Position racks in the upper and lower thirds of the oven and preheat to 350 degrees F. Pulse the pistachios and 1 tablespoon granulated sugar in a food processor until the nuts are finely ground and powdery. Sift with the flour and salt into a medium bowl; set aside.
Beat the remaining 3/4 cup granulated sugar and the butter in a large bowl with a mixer on medium speed until light and fluffy, about3 minutes. Add the egg and vanilla and beat until combined. Reduce the mixer speed to low; add the pistachio mixture and beat until completely incorporated.
Fill a cookie press with the dough according to the manufacturer's instructions. Press cookies about 1 1/2 inches apart onto 2 ungreased baking sheets. Sprinkle with sanding sugar. Bake, switching the pans halfway through, until set and golden around the edges, 10 to 12 minutes. Let the cookies cool 5 minutes on the baking sheets, then transfer to racks to cool completely.