It looks like any normal lunchtime at Honest Burger in Kings Cross.

The chefs get raw pink patties out of a pannier and place them on the grill with a hiss that sends a delicious smoky aroma through the restaurant. They give the patties three minutes a side, until the surface is seared with brown marks, then arrange them on brioche buns and pile on melting cheese, spicy mayonnaise, lettuce, tomato and onion in the style of an American cheeseburger.

But this is not a normal lunchtime. This is the first time Honest Burger has served the “bleeding” vegan burger from US plant scientists Beyond Meat to the public, ahead of it going on sale at the Kings Cross branch on Tuesday July 10. The Beyond Burger is also about to appear in Tesco next to the animal meat burgers in the meat aisle and next to the veggie burgers in the frozen cabinet, sending a signal that this isn't just another meat-free burger for vegetarians but a product that its creators believe is as good as meat.

“We were the first meat-free burger to be stocked in the meat section at Whole Foods,” Seth Goldman, chairman of Beyond Meat, tells the room of eager testers while the burgers sizzle in the background. “When we first went there we thought could we hold our own. Now, in one of the California chains this is the top selling burger in the section, which shows the kind of people we are bringing to this space.”

Beyond Meat’s appeal to both vegans and meat-eaters has been key to its success in the US, where it is sold at the chilled meat counter alongside animal products at 8,000 grocery stores. Bill Gates and Leonardo DiCaprio are among investors who have plugged $72 million into the company since it was founded in 2009. Demand for the product is scaling rapidly. Production is expanding from one factory in Missouri to another three times the size. By the end of the year, the burger will be on sale in 50 countries across six continents.

In Honest Burger, the patties are delivered to the tables. On closer inspection, the burger looks even more like meat. The pink inside has a fibrous texture not unlike corned beef, while the smell makes my mouth water - and I haven’t eaten meat in 12 years. While I see none of the supposed bloodiness, the patty is succulent when squeezed and greasy and satisfying to taste, unlike any vegetarian burger I have ever tried.

The secret, the company says, is that rather than starting with vegetarian ingredients and trying to make something meat-like, researchers reversed-engineered a meat burger.

“Our founder took a different approach and looked at the burger from a molecular level,” Goldman says. “We started with water. Then we looked at amino acids and you can get many of the same acids from plants as well as meat. The protein and the texture we replicated with yellow peas. Then there is fats, so we used coconut and rapeseed oil. We then assemble the constituents using heat and pressure to stitch them together so it retains its juiciness.”

All of the ingredients are readily available to consumers, Goldman says, and the science behind the production is not dissimilar to how pasta is made. The difference is that Beyond Burger has created machinery to make patties at scale in a way that would be very hard to replicate in the kitchen.

Ethan Brown, the founder of Beyond Meat, grew up in Washington DC but spent time as a child on his family’s dairy farm, where he became increasingly uncomfortable with the the similarity between the cows on the farm and the cows on his plate. As an adult he elected to be vegetarian and eventually vegan. But it wasn’t until he was working as a managing director for clean energy firm that he felt compelled to do something about the contradictions of working in an industry doing good for the environment and going out and seeing colleagues eating steak dinners at night.

He started to think about how meat gets to the plate. In production and project management, the “bottleneck” is the one process in a chain that has a more limited capacity, reducing the capacity of the whole chain. In the the food chain, the process that changes plant material to meat is held up by the animal, which consumes vast numbers of crops, takes up space and requires a lot of water to come to maturity. He describes Beyond Meat as identifying the bottleneck - or the animal - and removing it.

Seth Goldman came to Beyond Meat after his company, Honest Tea, was bought by Coca Cola. Though he stayed on the Coca Cola board, Goldman became curious about plant protein after his wife read an article on the subject. In 2012, he went to meet Brown and learn more about the business. Soon he was in regular contact with Brown, advising him on the ups and downs of working for a food startup. “With a startup, not everything goes to plan,” Goldman says. “I think he found my insights useful.”

In his current role as executive chairman, Goldman is having fun introducing the burger to new markets and seeing the reactions of consumers. “Both Honest Tea and Beyond Meat is mission driven work,” he says. He points to health statistics that show the US ranks 31st on a list of countries by life expectancy, and the UK 20th. “I can bring out a zero calorie tea and a burger that has no fat and I’d be selling it to very few people. With Beyond Burger we are making a product that we sell to everybody.”

The partnership with Tesco is the result of two years of negotiations that began when Beyond Meat launched the burger in May 2016. Derek Sarno, director of plant-based innovation at Tesco, says the Beyond Burger fits with the Wicked Kitchen vegan food products that launched in Tesco in 2018, from vegan sourdough pizza to barbecue mushrooms. “Increasing the plant based everything is what we plan to do,” Sarno says.

For Honest Burger, which just opened its 26th restaurant in Bristol, the chance to serve the Beyond Burger was a no-brainer as soon as co-founder Tom Barton tried the product. From Tuesday 10 the burger will go on sale for £10.95 with fries at Kings Cross, served with vegan smoked gouda and chipotle vegan mayonnaise from Rubies in the Rubble.