A fixture on the Northwest Side, they started out some 50 years ago. First, with a hot dog stand, then a few trailers, and finally, a stand-alone store on the western edge of Irving Park Road. But since the 70s, they've been slowly changing their business plan.
"Business needed to be built up so, ma came up with a recipe - through friends and through the grapevine and we started a beef recipe," said Rich Bartell.
And they've never looked back. They begin with massive, Fred Flintstone-sized boneless cuts that get liberally seasoned with dried onion and garlic. Then it's into a hot oven for about an hour.
The temperature is dropped, and the beef roasts for another two hours. After it rests overnight, it's trimmed of excess fat, then sliced nearly paper thin on a large, mechanized slicer that shaves the beef into manageable sheets. While the beef is sliced, a gravy of drippings, seasoning and water is heated in the kitchen.
The sliced beef is dunked into the gravy, where it heats through. Six-inch, sturdy Gonnella loaves are overstuffed with the hot beef, and orders range from dry to juicy, with either sweet bell peppers or hot giardiniera - an amalgam of serrano chiles, carrots, cauliflower, celery and oil.
"Most common way is sweet, easy hot, easy juice. Some people say dip it, soak it," Bartell said. "We don't try to drown it in the juice like other people do 'cause it falls apart. We use a Gonella bread that holds it together pretty good."
More recently, Bartell has added a "trio" - which includes a three-inch version of the beef, along with a homemade meatball, and a small piece of sausage.
"Most people just eat our beef or our hot dogs, they don't try our sausage or homemade meatballs," he said.
The fries are hand cut and the chocolate shakes are extra thick. It's not gourmet, and it's not upscale, but for a couple of bucks, it's a Chicago institution that endures no matter what the trend is, especially after Easter.
"After that, it's back to the beef," Bartell said.
When Bob-O's opened some 50 years ago, they were known for one thing: their hot dogs. But over the last 30 or 40 years, the Italian beef has really been coming on strong, and you can bet that after Easter this place is really going to be packed.