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May 31, 2017
Fermentation 2.0

Ambitious chefs and home cooks alike are pickling sweet corn, crab apples, fish bones, and basically anything they want.

I remember the first time I made kimchi—almost 10 years ago now. My friend Bonnie Yoon was visiting Brooklyn from Los Angeles, and together we concocted her family recipe. We brined two heads of napa cabbage in saltwater for a couple of hours, then rinsed them and slathered the leaves, inside and out, with a slurry of garlic, ginger, scallions, dried shrimp, shredded daikon, salt, and ground dried chiles. We put everything in a big glass canister, squeezed it down to get rid of any air bubbles, and set it out on a kitchen counter to ferment at room temperature.

Three days later, it was ready. And what I remember of the taste was not the fire of the chiles or the funk of the garlic or the sourness of the cabbage leaves, but the effervescent mineral tang at the tip of my tongue. It was sharp, eye-opening, alive with flavor. There was something going on here, and it was damn delicious.

That taste—the taste of life, as I’ve come to think of it—has stayed with me. What is it, exactly? And how can I re-create it?

Not far from my home in Brooklyn is Mettā, a new restaurant whose executive chef, Norberto Piattoni, is dedicated to pickling, drying, fermenting—anything that will preserve ingredients beyond their traditional season. Bluefish bones, collard stems, scallions, watermelon radishes, butternut squash—all are treated to make them last months, even years, the bones dried, the stems salted and spiced, and everything brinable (which is everything) brined. Last summer, Piattoni even fermented sweet corn, and by March he was serving a salad of it—with herbs, chile oil, and a tomme-style cheese—the corn’s natural sugars and crunch preserved, transformed, and enhanced by a lengthy saltwater soak.

“In the winter [in New York], we don’t have anything to cook,” Piattoni—37 years old, long-haired, and wearing an Adidas track jacket—explains to me in Mettā’s dining room. “But if you’ve been saving during the spring, summer, and autumn, you get into a winter with a lot of produce that you’ve been preserving.” His approach, he says, harkens back to a time before electricity, when failing to keep enough food around meant starvation. Or maybe to an era more recent than that: Piattoni grew up on his family’s farm, in Federación, Argentina, a town bordering Uruguay on the Rio Plata, about 300 miles north of Buenos Aires. There he learned to cook, but he also learned to game the seasons, preserving quality produce year-round. Although he studied chemical engineering at university, he soon veered back into the kitchen, cooking for Argentine super-chef Francis Mallmann for several years before moving to San Francisco, where as sous-chef at Bar Tartine he honed his fermentation technique.

“It’s always the same recipe,” he says. And it’s ridiculously simple: You make saltwater, then put your vegetables in it.

Okay, it’s more complicated, but only a little. The brine is 2.5 percent salt, so for every liter of water you use, you’d add 25 grams of salt. (Regular kosher salt is what Piattoni uses, since fancy, flavorful sea salts are too expensive for bulk use.) Into that brine, you put your vegetables—roots or alliums or snake squash or whatever.

Next, you cover the brined vegetables with a lid that you can press down to squeeze out the air and gas that bubble up as the produce ferments. Then you leave it at room temperature for 7 to 10 days, although Piattoni points out that’s at your discretion: “When you can taste the sourness that you want, and the texture that you want, and after that process is over, you should put it in cold”—that is, refrigerate it—“and it will stop completely that process.”

That process is the fermentation, essentially allowing airborne yeast and lactobacilli—bacteria that are present in the produce itself—to grow and to alter composition and flavor. Refrigeration puts a pause on all of this—well, mostly. The lacto-bacteria will go on converting sugars to lactic acid, and deepening flavors, albeit much more slowly. “The taste,” Piattoni says, “is a little more sour, savory, and cheesy-funky.”

The taste is also well within the reach of the home cook. I recently polled my friends to see if any fermented at home, thinking maybe I’d find someone who once made a batch of sauerkraut, but instead the lacto fans came out of the woodwork. One told me about his grandfather’s pickled cucumbers, whose fermentation formula included “sour homemade rye bread.” Another followed a Nepali recipe that involved sun-drying strips of daikon, then letting them mellow—in a jar in the sun—with turmeric, mustard seeds, mustard oil, chiles, scallions, and lots of salt. A lot of people liked to salt radish and mustard greens. No one was using fancy equipment—just Mason jars or a heavy-duty crock from Eastern Europe, with a heavy dish to weigh vegetables down into the brine.

For some reason, this freaked me out. The precise quantities of salt, the sterilization of fermentation vessels, the fluctuation of storage temperatures, the possibility of mold—how did they handle it all?

“Regarding mold,” says Fay Yu, a TV producer who likes to pickle crunchy veggies like carrots, cauliflower, and asparagus, it “helps to never grind the spices, just use whole. But if mold or yeast happens, just skim it off and take a tiny taste to see if it’s gone off.”

Down in Mettā’s basement, we took tiny tastes of everything—and nothing had gone off. In fact, these pickles had it going on. Crunchy-funky ramps. Salty-chewy butternut squash. Sharp black radishes. Each cycled through nearly every flavor—salty, sweet, bitter, spicy—before settling into a rich and intriguingly vegetal umami. All had something complex and lively going on.

“That light, funky sensation in the front of your tongue is lacto-bacteria,” Piattoni says. “You feel that sparkling, that something is alive in your mouth—it’s basically that.”

The technique can really be used on just about anything. Crabapples, for instance. After brining them, Piattoni says, “we find out that those apples become, like, exactly the same flavor and texture of umeboshi,” or Japanese cured plums. “It was this sour, savory, sweet flavor. We turned those crabapples into a paste, and that paste was turned into a sauce for a pork dish that we were doing.”

That’s kind of Piattoni’s cool trick: It’s not enough just to ferment good produce and eat it out of a jar or on a charcuterie plate. The pickles can be transformed again and again. That pickled butternut squash gets pureed and topped with green cabbage that’s both brined and charred, plus broccoli rabe flowers and dried habanero chiles. (Village Voice critic Zachary Feldman swooned over this.) And the sharp, acidic taste of these preserves is an excellent pairing for what is actually Mettā’s main attraction—an open-fire hearth in which Piattoni slow-roasts lamb neck, chars beets, and grills pork steaks. With all that heat and ash and caramelization, you need some pucker and crunch for balance.

Even the leftover brine has its uses. Last summer’s corn may be all gone, but its fermenting liquid has “so much sweetness from the corn” that Piattoni is thinking of turning it into a granità. Which is pretty brilliant: What could be better on a hot afternoon in July than last year’s sweet corn, given new life through the scientific magic of fermentation?

Matt Gross

Matt Gross writes about food, travel, parenting, and culture for lots of places. The former NYT Frugal Traveler and former editor of BonAppetit.com, he is the author of the travel memoir “The Turk Who Loved Apples” and lives in Brooklyn with his wife and two daughters.