Knotweed soufflé, anyone?

With knotweed and dandelions running rampant, chickweed choking the flower beds and ground elder invading the lawn, there’s a new solution for unwanted visitors to the garden. If we can’t beat those most persistent and prolific of weeds, we can eat ’em!

We’re not just talking nettle soup – every edible scrap from field, riverbank, sea-shore and hedgerow seems to be finding its way into the kitchens of the world’s top chefs, the more obscure the better. Viewers of the BBC’s Great British Menu have been observing this phenomenon for weeks – Nathan Outlaw topping his fish with gutweed, the head chef of Northcote Manor throwing garden rejects into soup – and now Noma of Copenhagen, voted best restaurant in the world, bragging about how many foraged goods they throw into their two-star dishes. “We cook with everything that surrounds us to express our ‘terroir’,” explains René Redzepi, head of the Danish establishment where every chef is expected to double as a forager. The cooks go out every morning, picking elderflowers, angelica leaves, beach mustard and wild roses.

One diner who was so impressed he has taken the concept wholeheartedly on board is Michelin-starred Nathan Outlaw, whose dessert of sea buckthorn freshly gathered near his restaurant in Rock, Cornwall, helped him win the South-West heat of Great British Menu. “It tastes like a cross between orange, lemon and passionfruit, though it doesn’t have the best nose,” he laughs, recalling Prue Leith wrinkling her nostrils up at the dessert. It must have been the gutweed, which Outlaw deep-fries and calls “a bit ozoney and salty” that won the prize.

“I only use weeds when they are right for the dish. I do think there is some stuff that isn’t so good,” he says, admitting he has been inspired by “a mad forager lady” who has introduced him to new ingredients. They include seabeet, which he uses as a spinach substitute, gorseflower, which finds it way into ice-cream, and pink purslane, dandelion leaves and wood sorrel, all for salads.

Meanwhile, in the Ribble Valley, Andrew Mellin is wheeling barrows full of bittercress, chervil and sorrel into Northcote Manor, whose Michelin-starred menu lists Foragers’ Soup as a staple. Mellin is their head gardener and if it were up to him they would also be cooking up ground elder – “most people are trying to get rid of it” – hedge garlic and other weeds he pulls from the ground and steams for supper.

“I’ve been doing this 25 years,” explains the man who has worked in the gardens of Sir Cameron Mackintosh and the Prince of Wales, who are as keen on garden rejects as he is. “Nettles, for example, are one of the most underrated foods,” he says, explaining how he mixed his with mashed potatoes and chicken stock: “There’s more vitamin C in them than oranges – and they’re free. I haven’t shopped for supermarket vegetables for 25 years!”

Food writer and keen forager Elspeth Pridham makes soup out of her ground elder, mixing it with peas, “though it was originally introduced by the Romans as a salad leaf”. She has also enjoyed foraged produce at the Riverford Organic restaurant in Devon: “They make a great wild garlic risotto – and I hear the Railway Hotel in Faversham is garnishing every dish they served with foraged greens.”

Nettle soup and wild garlic risotto look positively tame beside the dishes created in Brighton using knotweed, the most reviled and invasive weed in the British garden. Olivia Reid of the restaurant Terre à Terre explains: “The Phlorum environmental consultancy got in touch to see whether we fancied cooking with it, and when we heard it tastes great, we jumped at the opportunity.” She describes the stalky beast, which looks like a cross between rhubarb and asparagus, as “lemony and zesty. It produces a wonderful liquor when braised, and works really well in a compote made with raspberries and ginger – a very versatile weed”. Best of all, she says, is the knotweed and shallot jelly served with Sussex slipcote cheese.

But knotweed will never make it permanently onto the menu of Terre à Terre or any restaurant. “It’s illegal to grow and possibly to harvest and dispose of, so it’s a problem for a catering kitchen. It’s fine to cook with garden knotweed but in fields it might be contaminated with chemicals.”

A good source of what to gather and how to cook it is Canterbury’s Fergus the Forager, who provides a wealth of information on Wildmanwildfood.com. If his pilaff and chickweed starter is not to your taste, there is sea buckthorn cheesecake, and a section on “leaf curd”, comprising proteins extracted from wild leaves, described by Fergus as “the future”. Given the doomsday scenarios about more conventional foods running out, it might well be.

Until supermarkets and greengrocers cotton on to the fact that foodies like weeds, keen foragers will have to comb their own gardens or the fields and hedgerows for edible weeds – although one product available is nettle jelly from Hawkshead Relish. “It works really well with goat, which we put it with on the principle that foods which grow together eat well together, but also with lamb and salads, with its light, fragrant, almost gooseberry overtones,” says jelly-maker Maria Whitehead.

“Picking nettles is not a favourite job, but once you have done it a few times you know how to do it carefully. I have come to love the nettle patch in our garden now.” The company has so far made more than 3,000 jars, and hopes to build on the popularity by bottling more wild produce.

As for what’s next, we can only look to Noma, which seems determined we should chuck nothing into our green bins that could go into our tums. Chef René is touting radishes in edible soil as a menu item … anyone for compost?!

How to cook with weeds

* Nettles make famously good soup, but it’s best to use young leaves, as more mature plants have the potential to cause a stomach upset.

* Ground elder works well with peas in soup, or lightly steamed to be served as a vegetable.

* Wild garlic can be used to flavour quiches or risottos or to add flavour to soups; both the leaves and the white flowers are edible.

*PInk purslane is commonplace, and popular as an addition to the salad bowl.

* Knotweed can be treated in the same way as rhubarb, cooked into a compote with sugar and ginger. But braised without sugar, it also produces a rich liquor which is good to add to savoury sauces.

* Sea Spinach is found on the shingle beaches and cliffs of southern England – look out for its glossy dark green leaves and reddish stems. It’s a distant relation of both beetroot and spinach. Steam, sauté or use wilted as a garnish for soup.