Wolfgang Puck has been a celebrity chef for more than two decades and is a mainstay on cooking and television shows like Masterchef and The Ellen DeGeneres Show.
His restaurant Spago in West Hollywood, which he opened in 1982, is considered a pioneer of California-style cooking, and is still a celebrity hotspot more than 30 years on.
Amid all that success, Puck's business empire now brings in about $600 million each year, he told CNBC. That includes his fine dining restaurants, casual restaurants and merchandise like cookware, knives, coffee makers and rice steamers.
The restaurant industry is tough, though, and even celebrity chefs often struggle to convert fame into profit. Passion, the Austria-born chef said, is what's essential for those wanting to venture into the restaurant industry.
"They have to have passion for food, the passion for hospitality. It's not a business where you sit in an office and just look at the computer and numbers. The numbers come after. First, you have to make the customer happy," he told CNBC during a visit to his restaurants in Singapore.
The city-state played host to the first international outpost of Puck's fine dining empire, and the chef said that his Singapore restaurants are the most profitable — as labor costs are lower. Last year marked the restaurants' best year, he said.
Despite his own international outings, he cautioned that expansion is a risky business. The restaurant businesses need to "expand at a certain pace — not too much and not too little," he said.
"You have to make more money than you spend, that's my first thing — I didn't have to go to Harvard or Princeton for that."
Now 68 years old, Puck has earned his stripes and could afford to slow down, but the Austria-born chef is pushing forward.
In fact, he is currently enrolled in Harvard Business School's Owner/President Management program — an achievement he is says he's proud of since he began culinary training at 14 and never graduated from high school or college.
"I learned a lot about negotiation, I learned a lot about marketing and how really to explain my vision better to everybody," he said, adding that he is now in the process of reorganizing the multiple companies in his business empire.
He may have opened restaurants around the world, but Puck credits Harvard for teaching him how to negotiate better.
"In the old times, it was my way or the highway. If you don't like it, forget about it," he recalled, saying that attitude was not particularly good for him or the other party. For instance, he pointed out that one of the first things a restaurant owner needs to do is to negotiate a good deal for the lease.
But he said he has since learned that a better negotiation tactic was to think about what the other party wants from the deal.
The chef said he has made his fair share of business mistakes.
He opened a restaurant-cum-brewery in 1989 and it seemed successful, hosting celebrities like Sean Connery and Julia Roberts. However, as the beer had been made the traditional way without pasteurizing, hundreds of cases went bad and he had to close down the business after two years.
"I learned from that, not to do anything that I'm not an expert at," he said.
That's why he advises aspiring entrepreneurs, including his son who is a young chef, to learn as much as they can before opening their own businesses.
"Gain as much experience before, make your mistakes so that way you don't have to pay for it, somebody else will pay for it. Once you open your own business, you'll have to pay for it," he said.