Christopher Kostow foraged in the open stalls of the Mercado San Juan, the most gourmet of Mexico City's crumbling, pungent public markets, as vendors hawked: "This way, this way! What can we offer you?"

Kostow, whose Restaurant at Meadowood in Napa Valley has three Michelin stars, wanted to sample the diversity of the country's fresh ingredients: gray oysters from Baja California, lychee-like hairy rambutan from southern Chiapas, and bags of red flying ants from Oaxaca.

Like other top chefs from around the world, Kostow comes to study and experiment with the purity of ingredients and flavors in real Mexican cuisine, now a top export commodity that was dismissed for decades as tortillas suffocated in heavy sauces, cheeses and sour cream.

"I don't know if you come to Mexico to learn what's new, but rather you come to Mexico to learn what's old," said Kostow, referring to the ancient cooking traditions of the many indigenous groups. "There are flavors of great depth, and there are techniques that are pretty challenging."

Though the movement has been slow, Mexico in the last few years has begrudgingly earned the respect of an Italy or France as a destination for the world's foodies, be they top chefs such as Kostow, who was crowned America's best new chef just three years ago, or curious foreigners in sandals writing food blogs.

Mexico's diverse terrain, from deserts and coastlines to cloud forests and jungles, has produced a vast range of flora and fauna that since pre-Hispanic times provided the ingredients for dishes that vary by ecosystem. It is the perfect model for the new global trend to cook "paleo" and eat local.

In Mexico, that includes worms, grasshoppers and insect larvae, long considered caviarlike delicacies that are now being introduced to a wider world.

"A lot of people that I know are sort of turning their eyes to Mexico as a new place where a lot of innovation is going to happen," said Lars Williams, the research director of the Nordic Food Lab in Copenhagen.

Star chef Alex Stupak, who runs a high-end taco joint in New York, visited a Mexico City street food stall and made a cellphone recording of cooks kneading masa dough to make huaraches, thick oval tortillas topped with cheese and steak resembling the leather sole for which they're named.

He is experimenting with pasta made from the same dough.

The leaders of this movement include Mexican chef Enrique Olvera of Pujol restaurant, a pioneer in the country's rediscovery of its authentic cuisine. He has been featured in local magazines as a young yet influential cook who has managed to modernize Mexico's pre-Hispanic food traditions in an elegant way.

His menu includes tostadas with escamoles, ant larvae, and green mole made with different types of ubiquitous Mexican herbs cultivated since Aztec times, known as quelites, that can range in taste from spinach salty to minty.

Olvera has traveled the world in the past few years, including Napa Valley and Copenhagen, forming a large network of the world's best cooks, most ranging in age from late 20s to mid-30s. His creative plates have inspired chefs such as Daniel Patterson of Coi in San Francisco, who said Olvera shows them not how to make Mexican food, but to incorporate Mexican flavors into their own creations.

"I like Mexican cooking, the depth but also the brightness, a lot of acidity," Patterson said.

Paxia, one of Mexico City's many new restaurants featuring haute cuisine, includes a plate of fat, delicately seasoned worms on its menu, as does Olvera's Pujol.

Soft tacos of crunchy grasshoppers or ant larvae seasoned with garlic, onion and green pepper are delightful to many Mexicans.

"How can you get gringos to eat bugs?" said Nordic Food Lab's Williams, who grew up in New York City.

Williams and his team experiment with Mexican techniques at the nonprofit lab established by chef Rene Redzepi of Copenhagen's Noma. One goal, he says, is to discover new flavors in edible bugs.

"We are trying to get insects to be seen as a very valuable commodity," Williams said.

Mexico's original food pilgrim, Diana Kennedy, who is considered the world's recognized authority on Mexican cuisine and has made a career of preserving its heritage, worries some of these chefs are mixing the wrong ingredients and "killing the flavor."

"Many of them are using it as a novelty and do not know the things that go together," she said. "If you are going to play around with ingredients, exotic ingredients, you've got to know how to treat them."

She also says these cooks may be biting off more than American or European clients can chew.

"It's going to be a very small public that's going to accept these very innovative things," she said.

Olvera recently invited a group of chefs to a Mexico City food conference where they shared ideas and dishes, and spent off hours exploring markets, kitchens and restaurants of their Mexican colleagues. They opened the conference with banquet featuring the fruits of their experiments.

Olvera presented a charred mushroom tamale that was smoked, not steamed, bathed in Serrano chile sauce that was just spicy enough to draw attention.

"In this time of year, it gets very foggy, like misty," Olvera said of his technique. "We added roots of cilantro, which is our way to say that our dishes have roots."

Stupak made crunchy waves of masa sandwiching shrimp, sea urchin mousse and roasted tomato sauce.

Up-and-comer Rosio Sanchez, a Mexican-American pastry chef at Noma knew she wanted something acidic to transform her Danish bitters dessert.

The Chicago-born daughter of two Mexican parents had the answer when she tasted the juice of the prickly pear, the spine-covered green paddles known in Mexico as "nopal," in a sorbet at Mexico City's Quintonil restaurant that she had the answer.

Sanchez asked chef Jorge Vallejo how he made it.

Easy, he said, you just stew the cactus leaves in salt and lime and smash them. The 27-year-old Sanchez, her sous chef and Vallejo smashed cactus late into the night at Vallejo's restaurant until they were a mess. Then they rinsed and pureed it.

Less than 12 hours before the banquet, she was juicing 20 kilos of cactus for her signature dessert, a disc made of whey with roasted agave syrup, milk ice cream, crumbs and small cookies.

The cactus juice gave it a taste that was acidic, then sweet and finally creamy.

"We were like, 'That's amazing,'" Sanchez said.