At Silo in London, the world’s first zero-waste restaurant, chef Douglas McMaster serves up 10 invasive species in a series of dinners that challenge our perceptions about how we should eat.

On the menu is the grey squirrel, which damages trees and has forced the now endangered indigenous red squirrel out of its natural habitat. It is presented as a deliciously rich broth, and as kŏftə with black garlic ketchup and chicken neck garum.

Then there are also American signal crayfish crackers, Pacific oysters topped with tart sea buckthorn, and tender Chinese muntjac deer steak with hogweed sauce. These species are wreaking havoc on local environments and endangering native biodiversity.

The star of the evening, however, is Japanese knotweed, probably the most invasive plant in the UK. In Japan, it is known as itadori, and is a prized spring delicacy sold in fancy farmer’s markets. In Britain, it is the bane of gardeners and homeowners as it can bring down the value of a property by 10 per cent if it’s found on the site. First introduced to Europe in the 19th century by a German-British botanist; the shoots of the fast-growing knotweed can penetrate and break up concrete.

At Alchemist raw moon jellyfish is marinated in rosa rugosa, a plant taking over the Danish coastline.
At Alchemist, raw moon jellyfish is marinated in rosa rugosa, a plant taking over the Danish coastline.

Many of the 10 courses at Silo feature knotweed, including a salad with cured egg yolk and brassica flowers, and a dessert of panela sugar ice cream and rose petals. The plant, segmented like bamboo and tasting like rhubarb, even features in the welcome cocktail created by Mr Lyan Studio, the creative consultancy set up by Ryan Chetiyawardana, the world’s most awarded bartender.

With these overabundant and easily accessible species, McMaster aims to be both sustainable — “our supply chain is less supplier to consumer, and more environmentalists trying to solve a problem” — and prove that such ingredients can be delicious.

“Turning diners and other chefs on to these ingredients is predicated on the dishes being done well. Ingredients need to be usable — a cultural shift will only be propagated on the excellence of the product,” he says.

(Related: Bulk food stores in Singapore: zero-waste grocery shopping)

Eating overabundant species to reduce pressure on the food system

Chefs have long had the power to effect a shift in what we eat. Take foraging for instance. Introduced a decade ago, it brought sea buckthorn, nettles, spruce and wild garlic into the spotlight and onto menus worldwide.

Will grey squirrel catch on and be served in restaurants across London, or the world? Or will American signal crayfish find their place alongside salmon and prawns in supermarkets? This remains to be seen.

But the idea of reducing pressure on the food system and the environment by eating overabundant species seems a no-brainer.

It is the overabundance, not the non-indigenous species, that is the key. McMaster uses the term “invasive” as it implies the right associations, but overpopulated indigenous species are also on his radar as he isn’t fussy about semantics since he focusses on the principle of balance in nature.

Everything comes down to our food narratives: the stories we tell about what we should and shouldn’t be eating. In many cases, food we consider fine, rare, or luxury has already changed — but our stories have yet to catch up.

Chef Daniel Humm World's 50 Best
Chef Daniel Humm of New York City’s Eleven Madison Park.

Daniel Humm, who converted New York City’s Eleven Madison Park, which has three Michelin stars, into a vegan restaurant, believes it is time for a new definition of luxury.

“We celebrate caviar as a luxury ingredient. But there’s nothing luxurious about caviar any more. It’s the opposite. It’s farm-raised, it’s flown in from afar, it’s not rare at all, and it doesn’t taste good… like it once did. It’s an old idea we’re holding on to,” he said when he took to the stage at the 2021 World’s 50 Best Restaurants awards in Antwerp, Belgium, last year.

By letting go of the old idea, McMaster is offering something new — an eco-friendly cuisine that lets chefs and diners indulge their curiosity, creativity and yearning to explore.

Japanese knotweed, anyone?

Zero-waste restaurant Silo serves up multiple renditions of the invasive Japanese knotweed.
Zero-waste restaurant Silo serves up multiple renditions of the invasive Japanese knotweed.

Around the world, other chefs are also experimenting with overabundant species. In the Nordic region, Japanese knotweed is already a popular ingredient, appearing on menus at Noma, the World’s Best Restaurant of 2021, and the sustainability-oriented Amass, both in Copenhagen.

Knotweed can also be found on US menus, where, like in the UK, some states require a licence for handling it. It is available at Daniel Boulud’s two-Michelin-starred Daniel, and at Amanda Cohen’s vegetarian restaurant, Dirt Candy, both in New York.

Known for its seasonal soups, Tian serves a version with Jerusalem artichoke, an invasive species in Austria.
Known for its seasonal soups, Tian serves a version with Jerusalem artichoke, an invasive species in Austria.

In Tian, Vienna’s innovative Michelin-starred and now newly Michelin-Green-starred vegetarian restaurant, chef Paul Ivić pickles it and uses it fresh, similar to rhubarb. He also makes syrup and vinegar from robinia, commonly known as black locust, and uses bushy knapweed and Jerusalem artichoke, a vegetable that is considered an invasive species in Austria.

Another chef who is leading the conversation about invasive species is provocateur Rasmus Munk, whose two-Michelin-starred Copenhagen restaurant Alchemist is an immersive dining experience. In his 40-plus courses of food, drinks and theatrical performances, he serves species that are invasive in Scandinavia.

Double Trouble is raw moon jellyfish marinated in rosa rugosa — a plant native to eastern Asia, where it grows on beach coasts, often on sand dunes — that is taking over the Danish coastline. Another dish, Butterfly, is an invasive cabbage white butterfly served perching, wings and all, on cryogenically frozen flowers in a broth made of more butterflies.

To ensure they are free of pesticides, these are farmed, rather than collected from the wild. Despite the dish’s high-protein, organic credentials, however, Munk admits it is not universally appealing. “Not everyone is able to eat the butterfly,” he chuckles. “And the dish created a shitstorm on social media.”

Munk may not be directly reducing the number of cabbage whites in the wild — how much impact a single restaurant could have on curbing an overpopulated species remains questionable — but he has sparked conversations about the impact of invasive species and their culinary potential.

Another Alchemist dish, Marine Invaders, is a purée of Faroe Islands sea urchin and foie gras topped with a cracker made from caramelised beach crab bisque. Both of these sea predators negatively impact Nordic waters.

A means to counter overpopulation

Amber’s Aka Uni; Despite its popularity, demand cannot keep pace with sea urchins’ relentless expansion.
Amber’s Aka Uni; Despite its popularity, demand cannot keep pace with sea urchins’ relentless expansion.

Denmark is not the only country suffering from an overpopulation of sea urchins, whether they are indigenous or introduced. From Canada to South Korea, and California to Tasmania, stretches of coastline are being turned into underwater deserts as purple sea urchins devour the kelp that provides habitats for other marine species. Several factors have caused the population of purple sea urchins to explode, including a disease that affects sea stars, their natural predators, as well as pollution and rising sea temperatures.

Serving sea urchins sustainably

SingleThread Restaurant
SingleThread Farm Restaurant in Healdsburg, California.

Uni, the golden tongues of their sex organs, wrapped over sushi rice, is the most popular way to eat sea urchins in Japan. It is considered a delicacy and an aphrodisiac for its creamy texture and soft, briny flavour that is slightly sweet and bitter. Despite its popularity, however, demand cannot keep pace with the urchins’ relentless expansion. Sea urchin barrens have persisted off Hokkaido for 80 years.

Outside of Japan, uni is less common, although some of the world’s best chefs have mastered its appeal. Ferran Adrià famously served the gastronomy world’s first foam with white beans and sea urchins in 1994 at his now defunct El Bulli in Catalonia, Spain.

Executive Chef Richard Ekkebus, one of Hong Kong’s leading lights in sustainable gastronomy, has long served uni at Amber, his modern European restaurant that recently earned a Michelin Green star alongside its two red stars. He sources sea urchins for his signature Aka Uni — cauliflower purée, lobster gelée and uni topped with Daurenki Tsar Imperial Caviar and gold leaf, and beautifully served in an urchin shell — mainly from Jeju in South Korea, or California.

As a result of the severe sea urchin problem on the California coast, the team at the three-Michelin-starred and Green-starred SingleThread Farm Restaurant in Healdsburg, California, has come up with dozens of ways to blend the velvety creaminess of uni into their Japanese- influenced dishes. Other chefs across America have followed suit.

Chefs like these change the narrative of gastronomy, telling a story that reflects our ecological present. Their focus has shifted from the rare and the costly to a cuisine bolstered by environmental health.

As McMaster says: “We have preconceptions of luxury, but it’s all a story, a romance popularised in culture. It’s a story we can change.”

(Related: Take a peek at the new Noma 2.0)

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