At 8 P.M. on Wednesday, the White Castle in Bushwick, Brooklyn, in the shadow of the elevated M-train tracks, was closed for a private party. Eric Wareheim, of the comedy duo Tim & Eric and Aziz Ansari’s show “Master of None,” played host, greeting guests at the door, wearing a sharp blue suit with a crisp white shirt, louchely unbuttoned at the chest. Questlove, his signature pick tucked into his Afro, was spinning records, warming up for a promised live performance by Ghostface Killah. The chef Danny Bowien, of Mission Chinese, wandered around looking amused.

The occasion for the festivities was the launch of a new White Castle menu item: sliders made by Impossible Foods, the Silicon Valley startup, founded by a Stanford biochemist, which has developed a hundred-per-cent plant-based hamburger substitute that mimics the molecular structure of beef, even approximating the way a real burger “bleeds.” (Ingredients include wheat, coconut oil, potato protein, and soy.) Servers hired specially for the event circulated trays of pale, crinkle-cut French fries, quickly-cooling onion rings, and sliders wrapped in wax paper and impaled with little paper flags that read “Impossible,” as if each one had been conquered by a miniature Neil Armstrong.

View more

White Castle is not the first restaurant to offer Impossible burgers—you can find them at more than a thousand establishments in the U.S., including at chains like Fatburger, Bareburger, and Wahlburger—but it is the first major fast-food chain to serve them, and in some ways the least likely pioneer. Founded in Wichita, Kansas, in 1921, White Castle is often credited as the country’s very first fast-food chain, and its burgers—small, square-shaped, ultra-simple, and sold for just eighty-one cents each, $6.99 for a sack of ten, or $19.99 for a “Crave Case” of thirty—are iconic. The brand boasts a solid cult following (significantly boosted, no doubt, by the 2004 stoner comedy “Harold & Kumar Go to White Castle”), and pre-assembled, frozen sliders are sold pretty much anywhere frozen food is. But White Castle feels, in some ways, forgotten by time, and it has not previously seemed interested in reinventing itself with progressive gimmicks like “healthy choice” options—though it does offers a regular veggie burger, “chock-full of carrots, zucchini, peas, broccoli, spinach, and more!” (Kim Bartley, White Castle’s chief marketing officer, told Forbes that partnering with Impossible is “one more way we can satisfy the evolving hunger more customers have for plant-based proteins.”)

When I first tried an Impossible burger, a few years ago, at Momofuku Nishi, David Chang’s Italian-Korean restaurant in Chelsea, I was impressed, if not entirely won over. It looked like a burger, down to its medium-rare-pink interior, and smelled like a burger, and even very nearly tasted like a burger, at least in texture. But in an upscale restaurant like Chang’s—where a beef patty would surely have been made with minerally, clean-tasting, grass-fed, freshly ground local meat—the Impossible burger felt slightly hollow, missing its burgery essence. The White Castle slider, though—which débuted on Thursday at a hundred and forty locations in New York, New Jersey, and Illinois—was surprisingly satisfying. It was blanketed in a rubbery yellow slice of what was allegedly smoked cheddar cheese, and sandwiched with a squirt of ketchup, some cooked onions, and a couple of pickle coins in the chain’s signature soft white bun. Unlike its beef equivalent, it was round instead of square, comparatively hefty, and a little crumbly, in the manner of a fairly loosely packed patty. Its edges were crispy and caramelized. Unlike the Nishi version, it was, in true fast-food-burger form, well done, although I did make out a bare hue of pink in the center. It tasted vaguely of mushrooms, but mostly just of salt and fat.

Photograph by Noah Devereaux / Care of Chan

A tray of regular sliders materialized, and I grabbed one of those as well. The beef, by contrast, was as compressed as a slab of bologna, or a shaved sliver of meatloaf, and as gray as the sidewalk throughout—which is not to say it didn’t taste good. It did, especially after half a Tiki cocktail, adorned with edible flowers in a White Castle paper soda cup. It gave me that primal satisfaction that seared animal fat usually does. But if I were presented with the choice of a burger made with cheap beef—probably inhumanely raised, definitely bad for the environment—or a plant-based alternative that tasted this close to the real thing, I’d go for the Impossible burger.

Around nine-thirty, Wareheim grabbed the mike to tee up remarks by White Castle and Impossible Foods execs. David Lee, Impossible’s C.F.O. and C.O.O., told the crowd, “Every burger you ate, versus a burger from a cow, saves the world ninety-five per cent of the land”—someone shrieked their approval—“seventy-five per cent of the water”—longer, louder shriek— “and produces an eighth, one-eighth, of the greenhouse gases.” This last number elicited a “fuck, yeah,” followed by an ear-curdling scream. “So you can have a delicious burger with no cholesterol, and have a great time.” As Ghostface began his set, a middle-aged man wearing monogrammed White Castle chef’s whites—he was Phillip Bach, White Castle’s head corporate chef and director of product innovation—peered out from the kitchen and complied eagerly with the rapper’s request for a call-and-response: “When I say ‘Wu,’ you say ‘Tang!’ Wu!” “Tang!” “Wu!” “Tang!”

The next day, at lunchtime, I took the PATH train to Jersey City, to another White Castle, among a cluster of Indian restaurants and grocery stores near Journal Square, to see the rollout in action. I expected some sort of fanfare: free samples, maybe, or at least a big banner or sign. But, scanning the menu above the glassed-in counter, I grew worried: the slider wasn’t even listed. I approached a cashier. “Do you have the Impossible burger?” I asked. “Oh, yes,” she said, and handed me a few promotional flyers. I asked if a lot of people had been ordering it, and she nodded, unconvincingly. Upon overhearing us, a middle-aged woman lingering by the pickup window chimed in, “I got it!”

“I’ve read about this, when it was in the laboratory,” the woman, whose name was Fran, told me, taking her Impossible slider out of its paper sleeve and gesturing with it as she spoke. She lived in another part of Jersey but was in the area for a podiatrist appointment, and had come to White Castle as a nostalgic treat; she’d been eating at the chain since she was a kid, she told me, when a beef slider cost just twelve cents. She had assumed that an Impossible burger would be expensive and hard to find, and was surprised and delighted to discover it at White Castle, and for only $1.99. “I don’t like to eat a lot of beef,” she said. “I’m into organic food, as much as I can afford it.” She took a bite of the slider. “It’s good. It’s mushy. With vegetarian burgers, they’re usually a little firmer than this, but this is very tasty.” She took a few more bites. “It’s delicious,” she decided.

After Fran left, off to the podiatrist, I sat and watched the lunch crowd ebb and flow. A construction worker ordered “sixteen burgers, no onions, six without cheese.” A woman wearing a hairnet and a Blue Apron hat opted for chicken sliders. No one mentioned the Impossible slider. Then a large man with a gray ponytail bounded up to the counter and studied the menu. “I haven’t been here in so long I’ve forgotten what you have!” he said. The cashier saw an opening: “We have the Impossible burger, if you want to try something new!” “The what?” the man asked. “The Impossible burger!” the cashier said, without any further explanation. “Impossible burger!” the man said, laughing. “I’ll tell ya what, I’ll stick with what I know.” He ordered a combo, the No. 1: French fries, a soft drink, and four Original beef sliders.

A previous version of this article misidentified the M.T.A. line that runs on the elevated tracks near the White Castle in Bushwick.