Step 1Sift together the flour, powdered sugar and salt.
Step 2In the bowl of a stand mixer fitted with the paddle attachment, cream the butter on high speed for about 3 minutes, until light and fluffy. Add the orange zest and beat on low speed for 1 minute. With the mixer on low speed, add the flour mixture, pausing to scrape down the sides of the bowl. Be careful not to overbeat.
Step 3Divide the dough into 2 equal portions. Roll each into a log about 1 1/2 inches thick and 5 inches long. Pour the raw sugar onto a sheet pan and roll the logs in it to coat evenly. Wrap each log in plastic wrap. Refrigerate for 1 hour. (The logs may be frozen for up to 2 weeks. If frozen, defrost in the refrigerator overnight to use.)
Step 4Heat the oven to 375 degrees. Line a baking sheet with parchment paper. Cut the dough into three-eighth-inch slices and place on the baking sheet. Bake for 12 to 15 minutes, until the edges turn light golden brown. Transfer to a rack to cool.