First, understand that an Italian beef shop, of which Chicago has scores, is not the sort of place where waiters patiently explain the menu—most don't have one—and order takers do not mollycoddle confused customers. Thus, it is crucial to know the lingo. Order "a beef," not "a beef sandwich." The latter is redundant, because all Italian beef is served in a sandwich.

"Double-dipped" says you want the whole sandwich submerged in gravy after it's been assembled. "Dry" is the opposite: a request for the server to pluck a heap of sliced, oven-roasted meat from the pan with tongs and shake off the excess juice before packing it into the bread. Say "hot," and your beef will be topped with the spicy pickled-vegetable relish called giardiniera; "sweet" refers to a garnish of roasted peppers. "Combo" means the sandwich gets freighted with a length of charcoal-cooked Italian sausage. Cheese and any other condiments are anathema.

Even ordered dry, an Italian beef is tremendously messy, often presented wrapped in waxed paper, which instantly gets blotched with juices. Some of the best purveyors forgo table seating altogether and provide customers with a chest-high counter where they can stand, unwrap the serving shroud, and scarf down the sandwich. Proper form demands that you do as Chris Pacelli, of Al's #1 Italian Beef, clued us in to do the last time we visited his family's 73-year-old institution, on Taylor Street: "Assume the Italian stance!" This means lean your elbows on the counter, spread your legs, and put your feet back as if you're about to be frisked. Using the thumbs-together grip you'd use if you were a strangler, grab the sandwich and hoist it to your face, never letting your elbows leave the counter. This allows you to tear off big bites of bread and beef and for debris to fall onto the wrapper, which makes a handy drop cloth. When finished, gather up the paper and toss it in the trash can, leaving the counter clean and ready for the next Italian beef eater. —Jane and Michael Stern, authors of Roadfood Sandwiches (Houghton Mifflin Company, 2007)