A fast-casual chain based in Chicago is known for their legendary Chicago-style hot dogs, which are never served with ketchup

Portillo’s is a fast-casual restaurant chain that many call the one-stop shop for iconic Chicago foods. It has a world-famous chocolate cake, an Italian beef sandwich, cheese fries, a chicken croissant, and a chopped salad. The most popular menu item is the restaurant’s Chicago-style hot dog, topped with mustard, relish, onions, sliced tomato, pickles, peppers, and celery salt. Insider's Herrine Ro visited the downtown Portillo’s location to learn about what goes into the hot dog and find out from customers why they think the Portillo’s hot dog is the most legendary in the city. Herrine ate some of the most popular dishes and invited her friends Alana Yzola and Kyle Desiderio to try out the dishes.