An ode to the oyster mushroom, the fungi that’s more than food

If any food will save the world, perhaps it is oyster mushrooms (Pleurotus ostreatus). You think I exaggerate. But what other ingredient can cleanse soil of toxins, insulate houses, provide easy-to-grow protein at low cost and yet taste so suavely delicious that you might believe you were eating a luxury piece of seafood rather than a fungus? And I haven’t even mentioned their weird beauty. An oyster mushroom’s smooth, pale cap resembles an oyster — hence the name — but the froth of off-white gills underneath can be as exuberantly frilly as a ballet skirt.

I only started to notice how interesting oyster mushrooms could be last year with the publication of Mezcla: Recipes to Excite by Ixta Belfrage, a Brazilian-Italian recipe developer who lives in London. Oyster mushrooms are one of Belfrage’s signature ingredients. In her recipe for crispy oyster mushroom skewers with crushed chickpeas, she declares that “there is a hierarchy of mushrooms, in my opinion, and oyster mushrooms are right at the very top, along with porcini.” Another of her recipes, oyster mushroom noodles with caramelised caraway onions, has become one of my most-cooked midweek dinners. The mushrooms are roasted and then made into a pasta sauce with cream, caramelised onions, caraway seeds, lemon juice and dill. The flavours have a comforting eastern European vibe. Belfrage says it is inspired by mushroom pierogi. But the crucial element for the texture is the oyster mushrooms, which add a pleasing meaty chewiness without which the dish could be a bit too soporific.

The potential of these particular fungi as a meat substitute was discovered more than a century ago. They have long grown in the wild on the trunks of dead trees but it was only in 1917, during the first world war, that a German scientist called Flack figured out a way to cultivate them. It was just after the so-called “Turnip Winter”, when hundreds of thousands of Germans suffered terrible hunger. Flack’s idea was that cultivated oyster mushrooms, which have a higher protein content than portobellos or chanterelles, could be a subsistence protein to feed hungry mouths. It turned out they were much easier to grow than most other mushrooms and would happily make their home on anything from sawdust to straw to waste coffee grounds.

The oyster mushroom’s powers go beyond food. It is a great material for making insulation, trapping more heat than fibreglass. Still more impressive is its ability to remove toxins from the environment. In 1998, the mycologist Paul Stamets was experimenting with some badly contaminated soil that had been drenched with diesel and oil. After just four weeks of growing oyster mushrooms, he found the soil had lost its toxic smell and returned to a light brown colour. After eight weeks, the level of petrol hydrocarbons in the soil had fallen from 20,000 to 200 parts per million. In that time, the mushrooms also ushered in a whole new ecosystem of insects, birds and a variety of plant species. “We felt we had witnessed a miracle,” Stamets wrote in his 2005 book Mycelium Running. “Life was flowering on a dead, toxic landscape.”

Eating these delicate fungi can feel like a miracle too, at least when they are cooked with care (cooking is essential because they contain a protein which can be mildly toxic when raw). One of the most delicious morsels I’ve eaten recently was a little pre-dinner snack at Rovi restaurant near Oxford Street created by chef Neil Campbell. Pieces of oyster mushroom were coated in a polenta crust studded with spices, then deep-fried and served with a piquant green tomato sauce and a wedge of lemon. It tasted so chewy in texture and savoury in flavour that it was impossible to think of it as a mushroom. Despite the name, the experience of eating them is closer to squid than to oysters. Their relative, the lovely king oyster mushroom, is sometimes used as an uncannily accurate vegan substitute for scallops in Asia.

Considering how versatile and healthy they are, it can be annoyingly hard to get hold of oyster mushrooms, at least in Britain. Worldwide, oyster mushrooms (in all their varieties, including the more unusual pink and golden ones) are now the third most cultivated type of fungus, behind the button/chestnut/portobello family (Agaricus bisporus) and shiitake. Yet in British supermarkets you can often only find oysters pre-sliced in plastic packaging as part of a pack of “mixed exotic mushrooms”. When possible, I buy them from a Chinese or Korean food shop or, best of all, loose from a fruit and veg market, where an added bonus is that you sometimes get a giant one which looks like a weird wonky flying saucer that a child might draw. It feels like a food from the future. Let’s hope it is.

Bee Wilson is the author of “The Way We Eat Now”

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