Constable: Visiting one of his restaurants, founder Dick Portillo still one of the crew

Watching Dick Portillo wait his turn behind other customers standing in the lunch line at the Downers Grove Portillo's restaurant tells you something about the man. An even better insight into his personality will come 90 minutes later as he's ready to leave.

Even though he sold his Portillo's empire to Berkshire Partners private equity firm in 2014 for a reported $1 billion, 79-year-old Dick Portillo strolls into this Portillo's without an entourage.

"I love the energy when you walk into Portillo's," he says, inhaling to take in the smells. An employee who gushes that she has worked at Portillo's "for 20 and a half years" hugs the charismatic guy with the gray hair and a tan. Others shake his hand.

"I get all the credit. They do all the work," says Portillo, who explains his success (and some of his failures) in his new book, "Out of the Dog House: Turning a $1,100 Investment into A BILLION-DOLLAR PROFIT."

The title references Portillo's first eatery in 1963, the Dog House, a 6-by-12-foot trailer built in Villa Park with the $1,100 life savings of Portillo and his wife, Sharon, and the carpentry help of his father-in-law and a neighbor. They remodeled the trailer to resemble a dog house, parked it in a shopping plaza and started selling hot dogs. And the rest is, well, not what you may have thought.

"I didn't know how to make a hot dog," Portillo says. "The buns were hard as a rock. The hot dogs were overcooked. The french fries didn't have a consistent taste."

Without a bathroom or running water in the trailer, Portillo had to string together 250 feet of green garden hoses just to fill his steam tables. One late night, as he and Sharon were washing the pots and pans in their bathtub, nobody would have blamed the exhausted couple if they burst into tears.

"How many people can claim they have a mustard ring in their bathtub," Portillo quipped. "We were rolling on the floor laughing. That's a great memory."

A lousy high school student, Portillo worked 14 jobs in the first 18 months after he married Sharon, when he was 19 and she was 17. He hated working in a foundry, a junk yard, a post office, several factories and in a railroad yard unloading boxcars. He couldn't endure another failure with hot dogs. "Fear was my fuel," Portillo says.

"I can't tell you how many nights I stared at the ceiling and said, 'Am I making a mistake?'" Portillo says.

At Argo High School in Summit, where he met his future wife but also had a tendency to get into fights, Portillo figured he was a "dummy" and a "screw-up." Seven days after graduation, he enlisted in the Marines.

"I learned a lot about how to treat people in the Marines," Portillo says. The kindness of Lt. Barney Brause had such an impact on his life that years later Portillo hunted down Brause and treated him to several exotic vacations. Portillo gives cruises to longtime employees and sends his most veteran staffers on trips to wherever they want in the world. He and Sharon split time between their mansion in Oak Brook and their luxury home in Naples, Florida, where he bought property and tore down a house just so he could build his house with a boat slip big enough for his 130-foot yacht.

It's a lifestyle Portillo couldn't imagine growing up in a two-story row house in the Mother Francis Cabrini Housing Project on Chicago's Near North Side. His father, Frank Portillo Sr., was born in Mexico and moved to Texas as a young boy. His mother, Stravoula Docas, was born in Greece. Neither finished elementary school. His dad didn't make much money working in factories. Portillo remembers how his mother once got caught stealing a pair of children's shoes from Montgomery Ward, and how they had to sell his tricycle to buy food. When his father got better jobs in sales and insurance, the family moved to better neighborhoods.

"If I came from a different background, it might have been different," says Portillo, who credits his childhood for making him so driven to succeed. He says he got his business training at "Asphalt University."

"I have a learning disability. Things don't come easy for me," Portillo says. In forming his business philosophy, he focused on training people to be part of the Portillo's culture. He decorated his restaurants with antiques and "junk" that he purchased at the Kane County Fairgrounds. He focused on the look, the smells, the variety of food, and the feel of the place. Doing many things well and making the process too complex to copy served as a "moat" around his Portillo's kingdom, he says.

As he added more restaurants across the nation, Portillo admits to paying a personal price as his sons, Michael, Joe and Tony were growing up.

"It's painful for a father to miss seeing his son catch a short pass over the middle and run 68 yards for a touchdown," Portillo says. "I missed birthdays, family gatherings, baptisms and other family occasions over the years. I can never get those days back."

He insists that his supervisors take time away from work to see their kids' games, concerts, performances and family moments. "Don't pass that stuff up. It's important," Portillo tells them. "If you do miss it, you'll be sorry later."

Married for 60 years, the Portillo had their first fancy meal at Richards Steakhouse, a long-gone restaurant where they ordered the cheapest thing on the menu - the chopped sirloin for $1.90. Portillo's longtime chief administrative officer, Patty Sullivan, recently found them a menu from that restaurant.

Sharon Portillo gave her husband a "Self-Made Man" sculpture by Colorado artist Bobbie Carlyle, which depicts "a man carving himself out of stone, carving his character, carving his future."

Sharon Portillo has Type 1 diabetes, and Portillo has donated millions of dollars to the Chicago Diabetes Project. He also has donated money to veteran charities, a local home for abused women and children, and Argo High School, which features The Richard and Sharon Portillo Performing Arts Center. He includes a "Dick loves Sharon" message, generally with a heart, somewhere on a wall in each Portillo's.

He owns other restaurants, shopping malls, apartments and other real estate across the nation. "I've got enough money, but frankly, making money is fun," Portillo says.

Our interview finished, Portillo walks toward the exit. Spying a dirty napkin on the floor next to the trash can, the billionaire bends over to pick it up and toss it in the garbage.

"The best part of my day was being in a Portillo's," Portillo says. "This is my baby."