Chef Rick Bayless poses in his 20-year-old Chicago restaurant, Frontera Grill. Bayless, credited with changing the profile of Mexican food in the U.S., received one of the top James Beard Foundation Awards during a ceremony Monday night in New York.

Chicago ? At a time when mole was still a one-syllable word, Rick Bayless asked Americans to discard nacho cheese notions of Mexican food and consider his experience of it – street food at once simple and complex.

Fresh from five years in Mexico, where the seasonal ingredients and nuanced flavors of traditional cooking had dazzled his palate, Bayless was confident American Mexican food could rise to that level of candid refinement.

Twenty years on, he’s been proved right. On Monday, his Frontera Grill – where straightforward style belies sophisticated, layered flavors – was named the nation’s top restaurant by the James Beard Foundation.

For Bayless, it signifies more than recognition of his own cooking. It speaks to the democratization of American food, which he says for too long treated Mexican food as a “downscale cuisine.”

“It tells you that food in America is not just one type of food, we embrace all kinds of cuisine,” he said, sitting in his restaurant’s eclectic bar the day after the award was announced.

“Because we are a melting pot of a country, we can fuse upscale dining with all sorts of ethnic cuisines in ways you just don’t see elsewhere in the world,” Bayless said.

Not that Frontera Grill is upscale, at least not by classic standards. Though sometimes gussied up for presentation, Bayless’ cooking strays little from the Mexican market foods that first inspired him two decades ago.

“Our food is anything but stuffy,” he said. “When you serve goat empanadas, stuffy doesn’t work.”

And Bayless’ food certainly works. Such as his ceviche yucateco, a mix of steamed calamari and shrimp bathed in citrus. It begins with a wave of cilantro that quickly mellows into lime and orange with lingering habanero.

Where American Mexican cooking often assaults the senses, Bayless’ hand with flavor and texture are both gentle and assertive. And his reliance on traditional technique and ingredients has offered an invaluable education.

“His was the first restaurant where you could really go and explore this cuisine and understand it’s not just about a whole lot of chili pepper,” said Ruth Reichl, editor-in-chief of Gourmet magazine.