Portillo’s Italian Beef Sandwich is a Chicago favorite. It has thinly sliced, slow-roasted seasoned beef on top of freshly baked French bread. For a real, strong flavor, dip the sandwich in savory au jus and garnish it with sweet peppers or spicy giardiniera. It’s one of the most famous things on the Portillo’s menu, and first-time visitors should definitely taste it. It’s juicy, tender, and full of flavor.