Portillo’s is a Chicago institution, a hot dog stand that was started in 1963 by Dick Portillo’s in a small trailer with no running water, and has now grown to 47 locations. Their chopped salad is famous. The Italian Dressing is from the Chicago Sun-Times. It is similar to the dressing found on salads at Portillo's and Maggiano's restaurants. Tip: If you make the dressing ahead of time and add a little bit to the cooled pasta and let it soak it up in the refrigerator for added flavor. Also, I believe chopped grilled chicken is in the original recipe.