Acorn syrup, root broth or wild bird's eggs? At the outer limit of organic cooking, some of the world's most innovative chefs currently are into a "primitive" back-to-nature cuisine whipped up with quintessentially natural produce.
The most radical proponents of the back-to-nature trend were a highlight of this week's annual Omnivore Food Festival in Deauville, gathering some 30 chefs from around the world for a show of avant-garde cooking.
And these new school chefs are taking the trend a lot further than France's celebrated chef Marc Veyrat, known for his walks through the French Alps in search of wild herbs and little-known flowers that eventually end up on the plate.
Slovenia's Tomaz Kavcic for example also likes to gather plants and flowers to brew up herbal teas or flavour the salt he uses to cook fish. And from country streams, he gathers stones and draws their water.
"He picks snowdrops and small primroses," said an interpreter as Kavcic prepared a "torrent-inspired" dish. "When he gathers stones there is moss. With all that he makes a soup, with bits of moss-covered wood, pine cones, primroses..."
Diners of Kavcic specialities are invited to plunge their hands in a bowl of icy mountain torrent water before eating fillets of trout laid out on a stone from the same torrent. The idea "is to offer a sensation, not only on the palate but also physically," said the chef.
Denmark's Rene Redzepi favours wild onions, wild thyme oil, wild sorrel, seaweed collected along the shores of Denmark or Iceland, the eggs of wild ducks, wild rosebuds and roots.
He mixes ashes from hay with beetroot juice and cooks it until it reduces to a dark jelly-like substance.
His Copenhagen restaurant "Noma" has a "field of vegetables" on the menu with tiny vegetables planted in mashed potato dished up on a stone from a field. The dish is sprinkled with malt and hazelnut powder that looks every bit like earth.
"There is a move towards more purity, towards the natural after years of doling out a very rich and very luxurious cuisine and then a decade of highly sophisticated innovative cuisine," Redzepi said.
"Nature is where we find our strength", he said, "and in Scandinavia we have a very pure virgin nature."
France's Cedric Denaux, chef at "L et lui" in the southern town of Saint-Paul-Trois-Chateaux, said "cooks are increasingly feeling at one with their environment and are now seeking to protect it."
Denaux, who trained as a botanist and "always looks down and picks up what I see", uses produce from his wife's vegetable plot to cook up root broth but also enjoys wild garlic, violets and acorns.
Food specialist Remy Lucas, who works for the Cate trends agency, says the latest new cuisine is anti-fast food and anti-pop food.
"There is a comeback to primitive cooking, a taste for the wild, an urge to swallow nature from a pre-cultural age," he said.
"People are saying let's cut to the heart," he added. "So what we're looking at here is prehistoric cuisine with basic produce, roots honey, small snails and broadbeans."