He is keen to try pickling nettles or thistles, having foraged at Gefiltefest with Rabbi Natan Levy, who says he was inspired by shmita year rules - that decree once every seven years you must let land lie fallow rather than produce annual crops. "It would have been a hungry time for ancient Israelis; without a harvest, they would forage to stave off hunger.
"While Hampstead Heath is no wild forest, it's the best Londoners can do, so we tried recreating this Torah-induced hunter-gathering moment for two hours on a Sunday morning."
It's an ongoing activity for Levy: "I have learned from expert foragers Shira and Jon Daniels what to look for and what to avoid. The main challenge is being open to new taste experiences.
"Once you get the foraging bug it's hard to stop - I've seen lawyers, doctors, even other rabbis lose themselves in the search for just the right blackberry. There's something elemental about eating from the wild earth."
He admits to an almost evangelical zeal. "I'm usually pushing some wild mustard seed or a nibble of lime tree leaf on any walking companion who is foolish enough to eat plants by the side of the road."
Levy loves to forage with his children who are very keen to join in a search. Occupational therapist Shana Boltin also found the younger generation taking readily to pickling when she engaged children in a pickle workshop at Gefiltefest. She learned the technique while on a Yiddish course in New York, and layers her vegetables with salt, spices, garlic and dill.
Talia Chain, who also learned fermentation skills in the USA, adds water to the salt and spices: "I cover the vegetables with a cabbage leaf to keep them submerged, otherwise you get mould forming," she says.
The mould, which is an occasional by-product of fermentation, is an unexpected link to her own paternal grandfather, Ernst Chain, who, together with Alexander Fleming, won a Nobel prize for discovering penicillin. "He had a professional interest in mould, but the grandparents on my mother's side I knew were so British they did their best to forget the traditions of the past."
Chain, who worked in fashion technology before switching to running community gardens, likes to mix up her pickles: "I currently have a jar of coarsely shredded red cabbage, cauliflower florets, onion rings and whole cloves of garlic all fermenting in a jar together.
"I avoid pickling cucumbers because the right variety is so hard to find, and bigger ones can go to mush. But pickled carrots are really great, and I love making sauerkraut with red cabbage as well as white, to which I add nigella and mustard seeds."
Not every vegetable takes well to a salt cure. "I tried pickling spring onions once and they were disgusting - they just went to mush."
Talia's husband, Josh Charig, is also a fermenter - of the grains that make good beer.
"I brew five gallons at a time in my father's garage in Stanmore," says the founder of Hellsize Park Brewing - named for the Belsize Park flat where he started brewing before flatmates objected.
Inspired by the proliferation of real ales and craft beers in bars and restaurants, Charig, who works as a search engine optimisation analyst by day, last year bought a mash tun in which barley and malts sit for several hours with water before being cooled and rinsed and hops added for flavour - a brewing process of nearly eight hours in total - after which one to two weeks of fermenting starts. He makes five gallons at a time, mainly for friends and events like Gefiltefest, where his samples ran out, and produced 300 bottles for his own wedding last year.
This kind of self-sufficiency - Charig and Chain dream of being able to grow all their own vegetables as well as make all their own beer, and Doctor also makes his own fermented drinks, including ginger ale - was driven by poverty in the shtetl. The new breed dedicated to gathering and preserving the harvest are more motivated by the satisfaction of what they can create at home, with a nod to the heritage with which they feel they have forged a link across the generations.
