Hot dogs in Chicago are a big deal.

Portillo's is a fast-casual restaurant that's located throughout Illinois and serves a classic Chicago-style hot dog.

Chicago is famous for its hot dog, which is an all-beef Vienna dog topped with mustard, neon-green relish, tomatoes, white onions, a pickle spear, sport peppers, and a shake of celery salt.

The perfect Chicago hot dog needs to have 'OBR' — the optimal bite ratio of toppings — according to Chicago food expert Steve Dolinsky.

The hot dog has historical significance in the city of Chicago. The all-beef Vienna dogs with the essential seven toppings nestled in a poppy-seed bun is a thing of culinary legend.

Even the award-winning, Michelin-star chef Grant Achez of Alinea — one of the best restaurants in America — tips his hat to his city's most classic food.

Portillo's, a chain resturant with a majority of its 53 locations scattered throughout Illinois, serves among other things, a classic Chicago-style dog.

Portillo's started as a simple hot dog stand in 1963. Known as "The Dog House," owner and founder Dick Portillo invested $1,100 into the business — only to grow his empire and reportedly sell it for nearly $1 billion in 2014 to Berkshire Partners.

While in town for the James Beard Awards this month, I stopped at Portillo's to see what all the fuss is about.

It's obvious the people of Chicago love Portillo's.

In 2014, right after the company was sold, The Chicago Tribune reported that the newer Portillo's locations brought in an average of $7 to $8 million annually. In 2018, at around 11:30am on a Monday, I expected the Portillo's on W. Taylor Street near down town Chicago to be mostly empty — but upon walking in, I found diners already wrapping up their finished meals and heading out for the rest of their work day.

I tried my first ever Chicago hot dog, and chatted about my experience with Chicago food expert and tour guide, Steve Dolinsky, whose insight into the city's favorite and most historic dish helped me appreciate it even more.