His fork decides fortunes.
"There's a guy who comes in, sits down and eats, and his experience will completely determine the fate of your restaurant," said Seamus Mullen, the chef-owner at Boqueria in New York City.
His mouth can make or break you.
"I remember when we were getting reviewed Tuesday night, I couldn't sleep," said Stephen Starr, the top New York City restaurateur behind Morimoto and Buddakan.
For good reason, according to Scott Conant of New York's Scarpetta. "I would say that if he likes your restaurant, you will be in business for a long time," said Conant. "If he doesn't, you won't be in business for much longer."
His palate? Raw power.
"Some kitchens I've been in, they stop service when Frank Bruni shows up," said Ryan Skeen, chef at Allen & Delancey.
CLICK HERE to read an excerpt of Frank Bruni's book. For the last five years, New York Times restaurant critic Frank Bruni has been, arguably, the single most powerful man in New York's big-money restaurant business.
"I'm looking for pleasure," said Bruni in a recent interview with "Nightline." "I'm looking for a good time. And I'm looking for no obvious shortcomings or flaws."
Bruni's opinions are like Supreme Court verdicts, with chefs living in fear of a critical death sentence. When Frank Bruni walks into your restaurant...
"The first thing I would [think], in your mind, is 'Holy s***, it's on, It's on right now!!'" said Scott Conant, chef at Scarpetta.
George Mendes of New York's Aldea restaurant added, "Frank Bruni enters and it's a rush of adrenaline. Then your stomach tightens up and you become really crazy."
He has inspired pure fear in the food business. But what does Frank Bruni fear? You might be shocked to hear that for much of his life, it was food.
"During my freshman year of college, I threw up a lot of my meals," said Bruni in a recent interview at Cafe des Artistes in New York City. "Whenever I would eat a meal that would get out of hand, I would throw it up. I took laxatives. Later on in college and later on out of college, I sometimes took amphetamines to try to control my appetite."
By the time he had resorted to amphetamines, Bruni had been struggling with controlling his appetite for decades. But when did it all start?
"You know, my mother used to always talk about a time when I was 18 months old and I was sitting in a high chair," said Bruni. "And she had fed me two good-sized burgers, and I threw a tantrum because she wouldn't feed me a third one. And that was sort of like the defining narrative of my childhood. I could just eat and eat and eat, and by the time I was 8, I was enough overweight that people were teasing me. My initials, F.B., stood for Fat Boy.
And once a fat kid, always a fat kid, Bruni said. The idea is at the heart of Bruni's revealing new book, "Born Round: The Secret History of a Full-Time Eater."
"It's kind of a metaphoric reference to being born with an enormous appetite and a predisposition to gaining weight," said Bruni. "And it also comes from a saying from my grandmother, which is 'Born round, you don't die square.' And what the book is ultimately about is the question of whether you can actually change yourself and your habits, over the course of my life and my struggle to do so.