What defines a delicacy? Some are wild foods; others are carefully cultivated. Some are highly seasonal; others are aged for years. But most are tied to the terroir of a particular place, and they’re usually labor-intensive, often prepared using methods perfected over generations. And they’ve got to be delicious, too. We asked six local chefs and purveyors to dish on gourmet goodies to learn more about where they come from, how they’re used and why they taste the way they do.

Photo: Alyssa DiPasquale

Phytoplankton

At O Ya, Boston’s swankest Japanese restaurant, you’ll find no shortage of fancy foodstuffs, from wagyu beef and foie gras to caviar, sea urchin and king crab. But chef de cuisine Nathan Gould’s current favorite is a less familiar delicacy: freeze-dried phytoplankton sourced from Veta La Palma, a sustainable fish farm in southern Spain. “It has this beautiful bright-green color,” he says, “and it gives this incredible flavor of the ocean.”

It’s also very expensive. Phytoplankton produce at least half of the planet’s oxygen and play a huge role as the first link in the aquatic food chain, but the individual organisms are microscopic in size, so 15 grams cost anywhere from $75 to $125. A little goes a long way. “When I first tried it, it was so intense,” Gould recalls. “I was like, there’s no way I could use a product like this.” But after much experimentation, he discovered that just a dash works magic in dashi broth as a base for soups, as well as in a butter sauce that he pairs with hydroponically grown spinach and caviar for the grand omakase tasting. “I just dialed it down really, really micro—like literally a microdose of plankton—into a butter sauce, and it turned it this wonderful oceanic flavor that really I’ve never had in any other food.”

O Ya, 9 East St., Boston (617-654-9900) o-ya.restaurant

Pu-erh Tea

Fine wines aren’t the only potables that improve with age. Pu-erh teas can grow more refined over time, too. “The oldest pu-erh I’ve tasted was from the ’60s, and it was really, really good,” says Suanne Scalise, director of training and education at MEM Tea Imports, which has supplied teas to scores of local restaurants and cafes for nearly two decades. “I definitely felt like my head was in the clouds for a few minutes.”

That heady brew is made from the leaves of Camellia sinensis var. assamica, trees that grow in the mountainous Yunnan province of southwestern China, where tea drinking is believed to have begun. “The trees are old, and they’re intermingled with other trees—camphor trees, pine trees—and all of the organic matter falling from these trees is feeding the tea plants,” Scalise explains. “You can taste that in the tea, which is really cool.” After harvesting, the leaves are processed as either “raw” sheng, a lighter, grassier sip, or “ripe” shu, matured in warm, damp conditions to encourage microbial fermentation and earthier flavors. Both varieties may be pressed into shapes, like round cakes called bingcha, which are wrapped in porous rice paper so the tea can oxidize more as it ages.   

“Once you open a fine wine, you’ve got to drink it, whereas with this, we can keep having a cup once a year and see how it develops,” says Scalise, who recommends storing bingcha in a cool, dry place away from the cooking smells of the kitchen. “If I bought one, I would put it in a shoe box somewhere in my closet, and I’m probably going to take off a chunk and taste it once a year with friends. Because it’s a shame to experience this stuff by yourself.”

$4-$83 at MEM Tea Shop, 196 Elm St., Cambridge (617-627-9500) memteaimports.com

Photo: Chattman Photography

Saffron

“I’m fascinated by rare spices that have particularly beautiful terroirs and, therefore, flavor profiles,” says Claire Cheney of Curio Spice Co. The shelves of her Cambridge shop are lined with such finds, from Cambodian Kampot pepper (“the Champagne of peppers,” she says) to Sri Lankan turmeric that Cheney grinds in small batches, releasing a richer aroma than supermarket counterparts. But the first spice to fascinate her was saffron.

Prized for the honeyed hay-like flavor it lends to rice, desserts and other dishes, saffron has long been used not only in food but in dyes, medicinal potions and perfumes—Cleopatra bathed in the stuff. The red threads remain the priciest spice on the planet because of labor-intensive production: A single pound demands the delicate stigmas of more than 50,000 Crocus sativus flowers. Cheney crouched in crocus fields to harvest them firsthand, volunteering on a saffron farm in the Kozani region of northern Greece, where she stayed with a family whose matriarch was known as the best picker in her village.  Today, Curio stocks saffron from a cooperative that includes that very same farm, sold on its own and paired with lemon verbena and bee pollen in a Kozani spice blend.

Cheney has visited other producers in a dozen countries in search of singular spices, but taste isn’t her only criterion. “Our mission with Curio is to reverse a lot of the effects of the exploitative spice trade that has been happening for the past couple of centuries,” she says. Operating Curio as a benefit corporation, she sources spices from socially responsible producers that compensate workers fairly and prioritize sustainability. That means she and her customers pay a little extra—but there’s a payoff in flavor and peace of mind, too.

$9 for 0.5 grams of saffron or 1.5 ounces of Kozani blend at Curio Spice Co., 2265 Mass. Ave., Cambridge (617-945-1888) curiospice.com

Photo: Tracy Chang

Jamón Ibérico de Bellota

Step inside Pagu, Tracy Chang’s Cambridge spot for Japanese and Spanish small plates, and you can’t miss it: In the middle of the dining room, on the corner of the counter flanking the open kitchen, a leg of Spain’s most pedigreed pig waits on a specially designed stand of granite and steel. This is jamón ibérico de bellota, a melt-in-your-mouth delicacy that only became available for import to the United States a decade ago. “Ibérico” refers to the heritage breed, while “bellota” means “acorn,” the staple of the pigs’ diet, which imparts heart-healthy fats—earning them the nickname “four-legged olive trees”—as well as a distinctive nutty taste.

“We wanted that deep nutty flavor,” says Chang, who fell in love with the pricey porker in Spain, where she worked for Michelin-starred chef Martin Berasategui. Now running a kitchen of her own, she sources jamón from Cinco Jotas, a 140-year-old purveyor whose purebred free-range pigs roam meadows in southwestern Spain. Their meat is buried in sea salt and aged for 36 months before reaching the restaurant, where it’s carved into ruby red slices, paper-thin and packed with flavor.
“Other ibéricos, or serrano, are definitely more affordable in terms of pricing and probably more approachable to the American palate,” Chang says. “But we intentionally chose jamón ibérico de bellota. It’s about being able to offer someone the experience of having that first ‘Aha, wow.’ ”

$16/$32 at Pagu, 310 Mass. Ave., Cambridge (617-945-9290) gopagu.com

Photo: Michael Pagliarini

Truffles

In the early 19th century, French gastronome Jean Anthelme Brillat-Savarin dubbed truffles “the diamond of cookery.” Fifteen years ago, while visiting Paris with his wife, chef Michael Pagliarini had a meal that made him realize what the fuss was all about: a truffle-filled feast at Alain Ducasse.

“I have the menu framed in our dining room,” Pagliarini says. “It was just this abundance of truffles with each course. I finally understood the appeal and the allure of them.” Now he serves them at both his restaurants, Giulia and Benedetto—microplanning fresh black truffles into a simmering pan of duck, red wine and butter to sauce pappardelle, say, or shaving white truffles tableside over fonduta-stuffed pasta cooked in brown butter and sage.

Tracking them down can be tricky. “You have to remember these are rare and unique wild foods,” says Pagliarini, who deals with purveyors who work with independent foragers in Alba, Umbria and Tuscany. “If you work with an independent forager, you’re often getting something that’s fresher, of a higher quality, and the price is a little better.”

That’s key because he wants to serve the sort of generous portions he experienced in Paris without eye-popping prices. So while diners at Benedetto can splurge by adding 7 grams of white truffle to any dish for $85 while they’re in season, they can also opt for a half supplement or half pasta; at Giulia, they might start a meal with warm semolina cakes with black truffles for $12. “We want it to be accessible, and we want people to experience them,” Pagliarini says. “We want to bring them to the table, let you see them, let you smell them. Ask to see them. Don’t be shy.”   

Giulia, 1682 Mass. Ave., Cambridge (617-441-2800) giuliarestaurant.com; Benedetto, 1 Bennett St., Cambridge (617-661-5050) benedettocambridge.com

Photo: David Robinson

Extra-Aged Comté Cheese

Formaggio Kitchen—the local destination for cheese and other delicacies celebrating its 40th anniversary this year—is the first and only American cheese shop to buy directly from Marcel Petite, a fifth-generation French affineur (cheese ager) famed for its Comté. Earning its trust was no easy feat. “When Ihsan and Valerie, the owners of the shop, first started traveling there, basically they were tested,” Formaggio cheese buyer David Robinson says. “They went in to taste, and they were grilled. They were asked, ‘What flavors do you taste?’ If they said hazelnut, the question was ‘OK, what kind of hazelnut? Where is it from? Is it raw, is it toasted?’ They had no idea if they were doing well or not.”

But they passed the test and went home with some 12-month Comté. It would be years, however, before the store could stock the affineur’s rarest cheeses: the grand cru and extra grand cru, aged for 24 and 36 months in Marcel Petite’s cavernous cellars in a former military fort in the Jura mountains. “Once Comté gets to the 20- to 24-month mark, flavors get much more concentrated,” Robinson says. “Not all cheeses can last that long, so they basically test wheels as they go to see if they can actually make it.”

Fewer than two percent of cheeses make the cut, so these extra-aged varieties are hard to come by. Formaggio started with an annual allotment of just two 80-pound wheels. As the friendship between the businesses has grown over the years, that allotment has increased to about 30 wheels—but they fly out of the case. December is an ideal time to look for them: Robinson visits the fort each year to select the holiday batch himself.

$32 and $40/pound at Formaggio Kitchen, 244 Huron Ave., Cambridge (617-354-4750); 268 Shawmut Ave., Boston (617-350-6996) formaggiokitchen.com