Following a successful test run in St. Louis, Burger King announced Monday that the chain will introduce its Impossible Whopper to more cities this summer, with the goal of adding the popular plant-based burger to menus across the country by the end of the year.

The news should thrill those who tied up phones at the chain’s outlets in the Gateway City, trying to have a mock-meat Whopper (or a dozen) shipped to California and other locales across the United States. But it will probably unnerve small, mom-and-pop restaurants that have struggled to get their hands on Impossible Foods’ alternative-meat patties since Burger King launched its new burger this month. Several restaurants in the Washington region have had to use other plant-based patties because suppliers have run out of the products from the San Francisco Bay area start-up.

At the Ted’s Bulletin chain, with five locations around the Washington region, the Impossible Burger is the fifth-most-popular sandwich on the menu, said Nick Salis, vice president of operations. The chain sells about 250 a week, he said. But since its Burger King debut, “we’ve been seeing shortages,” Salis said. Ted’s buys a couple hundred pounds of the bulk mock meat each week, but lately the supplier has had to fill about half the company’s order with a similar product from Beyond Meat, Salis said.

“The demand for it is not as good,” Salis said about the Beyond Meat substitute. “People are typically okay with the Beyond Burger as long as you tell them ahead of time.”

The Impossible Whopper, right, joined the Whopper on St. Louis area Burger King menus this month. (Tim Carman/The Washington Post)

Other restaurants report similar shortages. Big Buns Damn Good Burgers, with locations in Ballston and Shirlington, has experienced “supply interruptions for a little bit,” said Tom Racosky, co-founder and director of operations, but he added that Impossible Foods has been very responsive. At Quarry House Tavern, the popular dive bar in Silver Spring, operators have been without their supply for three weeks now, general manager Ellen Cox said.

“People are disappointed,” Cox said. “Rather than go for the vegan burger that we have now, they opt for the regular burger.”

These restaurant managers said the 2.0 version of the Impossible Burger has been a hit with diners, who don’t find other alternative-meat options as attractive. “The Impossible Burger feels, tastes and chews as close to a burger as I’ve seen,” said Salis of Ted’s Bulletin. That kind of customer demand has apparently surprised Impossible Foods, which has struggled to keep up with orders.

“We are straining to meet demand,” said David Lee, chief financial officer for Impossible Foods, in an interview with The Washington Post. “It’s a good problem to have, but it’s still a massive amount of growth at once.”

Impossible Foods has expanded its reach considerably in recent months. Last year, White Castle introduced an Impossible Slider to its nearly 400 locations nationwide, and this year, Red Robin debuted an Impossible Cheeseburger at its 570 locations. With the rollout of the Impossible Whopper, the burger could, by year’s end, find itself on Burger King menus at 7,200 locations across the country. That’s on top of Impossible Foods’ smaller customers, such as Ted’s, Quarry House and Big Buns. (Incidentally, when contacted, a McDonald’s spokeswoman said the chain does not have any news to share on a potential vegan burger of its own.)

Lee, the CFO with Impossible, said the company has a 70,000-square-foot facility that executives thought would produce about 1 million pounds of the plant-based meat a year. But now executives expect the facility to crank out between 75 million to 100 million pounds annually, all without expanding the plant’s footprint. Impossible Foods, Lee said, is adding more employees and adding more shifts to the facility.

“There will be some short-term dislocations and struggles,” Lee said. “But in the mid- to long-term, this technology was designed to scale up globally.”

Impossible Foods has been working with all its customers, large and small, to fill orders, Lee said. In some cases, the company has footed the bill to ship supplies by air to customers.

A regular burger at Quarry House in Silver Spring. (Deb Lindsey for The Washington Post)

Jackie Greenbaum, one of the Quarry House owners, forwarded an email that her general manager had sent to Impossible Foods on April 15, complaining about the lack of supply and asking if the tavern can purchase Impossible Burgers directly from the company. One day later, a representative responded.

“The current shortage is purely a question of there not being enough product to supply the skyrocketing demand that we’ve experienced recently,” the Impossible representative wrote back to Cox. “Within the next month — or potentially much sooner — your usual distributor should be able to meet your needs.”

Cox told The Post that she expects to start receiving Impossible Burgers again next month. But if not, Greenbaum said, the tight supply will force small restaurateurs to make a tough call.

“What will happen is,” Greenbaum said, “they will lose all their independent [clients] who are carrying it, because, at some point, you have to choose” the product with the reliable supply.

But then Greenbaum paused. She wondered aloud whether Quarry House would eventually switch back to the Impossible Burger even if the tavern were forced to go with a lesser product while the California company scales up capacity. She thought she would.

“The product is really that good,” she said.

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