Still, his classes at Hamilton College in upstate New York weren't time wasted. A thoughtful, disciplined approach is evident in the inventive, deceptively simple dishes that have won him three Michelin stars for his work at The Restaurant at Meadowood, located in a lush Napa Valley resort.
"Studying philosophy did teach me to absorb a lot of information with a critical eye and then use that information in a singular and personal manner," he writes in his first book, "A New Napa Cuisine," coming out this month. In cooking, with its different flavour memories and techniques, "whether or not I am successful is driven by my ability to retain this information, distill it through my lens."
Beautifully photographed, the book weaves together recipes, Kostow's evolution as a chef and insights on the farmers and craftspeople who help create the Meadowood dining experience.
Kostow, who had his first Michelin star before age 30, and in 2013 was named top chef in the region by the James Beard Foundation, cut his teeth culinarily speaking with a summer job frying chicken with a cast of characters that included a guy called Shaky the Clown.
But after college he moved to California with the idea of becoming a chef, getting a job after much perseverance at George's at the Cove in the coastal community of La Jolla. That was followed by stints in France, a job in a San Francisco restaurant and then the chance to be in charge of the kitchen at a small restaurant called Chez TJ in Silicon Valley.
It was here that he got his first Michelin star, in 2006 when the guide expanded to include the San Francisco Bay area.
"That was a big moment," says Kostow. "It was very much that first affirmation."
Now the holder of three stars at Meadowood he doesn't look at that as a burden. He's more likely to put pressure on himself if a VIP is coming in or, just as important, another chef. Then it's "Hey, this guy's coming in in two days. Let's get that dish figured out," he says.
Kostow's food is "creative, but grounded in the principle that the ingredient leads the way," says Tom Bensel, managing director of the Culinary Institute of America, also in St. Helena.
Much of the fresh produce on the Meadowood menu comes from a garden run as a joint project with the St. Helena Montessori School, which has a small farm across the street from the resort.
David Duncan, president and CEO of Silver Oak Cellars and a St. Helena Montessori parent, has been impressed by Kostow's work with the school.
"He is a cool customer. He is beyond his years in terms of maturity," says Duncan.
Duncan also recently worked with Kostow to prepare a 1,000-person dinner at the annual Auction Napa Valley last June. The event was a success, raising a record $18.7 million for local charities and the dinner went off well, too, right down to the 6,000 baby radishes, baby carrots and baby turnips that were grown in the restaurant garden.
And though he has a top chef's usual high-tech bag of tricks, Kostow's dishes reflect where the food came from.
"That's the thing that's so exciting when you go to restaurant at Meadowood," says Duncan. "It's really about place."