Stop a longtime Chicagoan on the street and ask him or her where the nearest Portillo’s restaurant sits, and the likely reply will not only include directions to the nearest eatery, but also suggestions of a few menu items to try.

Portillo’s is, after all, a Windy City treasure, a brick-and-mortar ballad to many things Chicagoans hold dear, namely hot dogs and Italian beef. And its origin is a testament to the city’s by-the-bootstraps, blue-collar ethos. The company is so beloved, in fact, that even when founder Dick Portillo sold his eponymous restaurant chain to Boston-based Berkshire Partners in 2014, Portillo’s average unit volume hovered north of $8 million and included a downtown Chicago location that tallied a whopping $17 million in annual sales.

“And that’s without a single parking spot,” says Portillo, who recently released an autobiography titled Out of the Dog House.

QSR sat down with the 79-year-old Portillo to discuss his fast-casual chain’s rise, its deep connections to Chicago, the keys to its success, and his decision to sell the business after decades of resisting overtures.

The secret sauce

In 1963, Portillo took the $1,100 he and his high-school-sweetheart-turned-wife, Sharon, had earmarked for their first home and instead purchased a 6-by-12-foot trailer. With no previous restaurant experience, Portillo opened a hot dog stand called The Dog House in Villa Park, a middle-class suburb located 20 miles west of downtown Chicago.

“I’m a hot dog lover, and Villa Park didn’t have anything,” he says.

Portillo set up The Dog House on a busy thoroughfare in the shadow of two large discount stores. But within weeks of opening, business was so slow that Portillo’s wife suggested the couple look for an exit strategy.