Watch out, Ottolenghi. Jamie Oliver is back with a vegetarian cookbook of his own

If Jamie Oliver's confidence has been shaken by the multi-million-dollar collapse of his restaurant empire, it isn't showing.

The zeitgeist-surfing celebrity chef is doing what he does best, demonstrating a new recipe from his latest cookbook, trademark grin firmly in place.

If it feels like there can be no more firsts, in a career that's spanned two decades, 32 cookbooks and 120 countries, his latest book, Veg, has yielded a surprising quality in Oliver – patience.

It's a virtue many long-time Oliver fans might have difficulty associating with the self-made multi-millionaire, who swiftly became one of the world's best-known TV chefs after being discovered in 1997.

"I wrote this book eight years ago [but] I was too early, and too early is a problem," the Naked Chef says, the words spilling out of his mouth enthusiastically as he strips a charred cob of corn of its blackened kernels for a sexed-up version of a Cobb salad that substitutes popcorn for croutons and yoghurt for oil to form the base of the zesty dressing.

Judging by the past few years of press and near-jubilation in some quarters as his beleaguered restaurant chain had its life support turned off in May, Britain's love affair with the dimpled boy from Essex has cooled somewhat as he took on new ventures and became a public health crusader, reforming school lunches, pushing for junk food ad bans and calling for the introduction of a sugary drinks tax.

Ottolenghi ... he's the primer, I'm the paint.

Jamie Oliver

Oliver readily admits to sounding "incredibly pretentious" as he explains why he put an unpublished book back in the bottom drawer instead of racing it off to print, despite forecasting, correctly as it turns out, that vegetarianism would gain popularity.

"The vegetable story, in my opinion, it's the food story of our time," he says speaking at JO headquarters in North London.

But was it a case of prophecy or catch-up?

In 2008, London's Israeli superstar chef Yotam Ottolenghi not just defined but owned the vegetarian space with his debut cookbook Ottolenghi, which he has followed with a string of veg-forward titles.

Oliver denies he's playing catch-up with Veg, because his market is completely different to Ottolenghi's inner-city devotees.

"No, no. I think partly the problem can be you're ahead of the curve and I think on this particular story it was waiting it out.

"I needed Ottolenghi to go in and do his thing. He's primed it, he's the primer, I'm the paint. So that's the way I'm looking at it."

Veg, which Oliver describes as his most important cookbook yet "from a symbolic and nutritional" perspective, is aimed at people like his 65-year-old father and those living in the suburbs, battling the everyday pressures of the school-drop off, commutes, careers and child-rearing.

Time is critical to his success. With titles like 30-Minute Meals, 15-Minute Meals, and 5 Ingredients – Quick & Easy Food, cooking time remains top of mind, even when he's in slow-cooking mode.

When interviewed ahead of the release of Jamie Cooks Italy in 2018, Oliver alluded to pressure from his publishers to produce another blockbuster.

Instead, he produced a book based on the old-school cooking of Italy's nonnas. He was at pains, however, to remind fans that alongside the weekend mega-dishes, there were plenty of Monday-to-Thursday recipes, as he calls them.

Oliver cites research into how long people are willing to spend preparing a nightly meal. Unsurprisingly, the figure has gone down drastically in his lifetime.

"Twenty years ago, when I started Naked Chef, the average was like 48 minutes. It's kind of gone down by 10 minutes every five years.

"The last big survey done was just over 20 minutes. That was three years ago. Three years ago we didn't have the Uberisation of food [with people ordering in rather than cooking at all]."

This constant time pressure means a few new rules in the kitchen.

Key among them is leaving nutrient-rich skins on vegetables where possible, a lesson Oliver says he learned too late in his career.

"I spent years peeling bloody vegetables. It's not the best fun and it takes quite a long time but actually most flavour is in the skin.

"You'll see in the book I'm not peeling much at all. So we're leaving skins on celeriac, we're leaving it on squash [pumpkin], we're leaving it on carrots and it really is incredible. I mean, it works. I promise you."

Oliver's flavour staples include vinegar, herbs, spices, curry pastes, pesto, miso, harissa, worcestershire sauce, dried mushrooms, tomatoes, parmesan and seaweed.

Nuts also figure prominently.

Oliver, who is now clocking three to four meat-free days at home, stresses that Veg is not about trying to convert meat-eaters, including himself.

"I could probably do a couple of months [vegetarian] if I had to but I would be a really bad vegetarian – you'd catch me with a sausage somewhere."

"Me being a meat-eater and me writing a veg book is just saying, 'maybe this is the time to eat a bit more veg, to try something new and maybe cut down the meat once a week'.

"I just think it's a really healthy conversation."