Like with most iconic foods, the origin story of the Italian beef sandwich is fuzzy.
But Chris Pacelli Jr., the co-owner of Al's Beef in Chicago's Little Italy neighborhood, credits his grandfather, Anthony Ferreri.
"He's the one who created this item," the 74-year-old said firmly, adding "the other guys are the copycats."
Here's how the story goes: Over 100 years ago, Ferreri, a street peddler, saw people at an Italian wedding slicing a roast beef with a knife and making sandwiches out of it.
Ferrari realized he could make a killing by cooking and slicing beef much thinner with his deli machine.
After some trial and error at home, Ferrari "presents it to the next guy who's having a party or wedding. And he tells him: 'Listen: For what it costs to serve 15-20 people. I could do 40 people for the same cost.'"
Today, Pacelli says the century-old recipe hasn't changed much — and the beef is still "sliced so thin that you can almost see through it."
The multi-day process starts with two 15-pound cuts of sirloin butt submerged in water with garlic, and 16 other secret seasonings.
After cooking for 3.5 hours at 425 degrees, the steaming roast beef is already scrumptious, even though it's far from ready to serve up.
The next step is straining and preserving the juice. Then, after cooling down the beef for 24 hours, it gets trimmed, sliced paper-thin and re-introduced to the simmering juice.
Finally, in the front kitchen, the sandwich gets assembled in three quick steps: Serving the dripping beef on a French loaf, dipping the whole sandwich in the juice; and adding the hot giardiniera.
SEE MORE: Drag It Through The Garden: The Chicago Hot Dog's Immigrant History
Chicago-style giardiniera, which means "from the garden" in Italian, is typically a medley of chopped and pickled vegetables. But at Al's Beef, they only use celery and spices, and let it all sit in vegetable oil for three days before serving it.
In addition to creating the sandwich, Pacelli says his family also invented how to eat it.
"We call it the Italian stance" Pacelli explained while demonstrating it. "You're going to stand back about a foot. The reason for this: You see how juicy the sandwich is? So when you eat it, it's going on the floor. It's not going on your shirt."
Today you can find Italian beef around the country. But Al's Beef customers say you have to go there for the authentic taste and experience.
"It's hard to find any beef like this anywhere else. I mean, it's impossible, really," said Tim Klein, who's been coming here for almost 40 years.
Another customer visiting from Phoenix used to eat here in the 1980s and gets emotional every time he comes back. "I don't mean to be melodramatic about it, but I do get wistful."
As for Pacelli, he says he is thankful to the TV show "The Bear" for putting his family's invention in the national spotlight. He says the show creators called him for guidance and to record his uniquely Chicago accent.
"We created a product that America could love. And we just needed someone to put it out there, present it to the country and the rest of the world," Pacelli said.
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