Anyone who has cooked one of Yotam Ottolenghi's recipes knows they are not 15-minute meals. The ingredients won't all be in most home cooks' pantries. Sourcing them often entails a trip to a large supermarket or specialist ethnic grocer.

Even once the ingredients are on your kitchen counter, preparation can involve toasting nuts or seeds; grinding spices; roasting, chargrilling or steaming vegetables; chopping herbs; juicing citrus fruits, whisking up dressings or, more likely, all of the above. Deceptively simple salads are often hugely labour intensive.

Hard work it may be, but it is always worth it. Which is why legions of Ottolenghi fans, will be drooling over his book, NOPI: The Cookbook, published a few days ago.

The book - a thing of beauty, with sexy, gold-edged pages and simple cover logo of a black pan edged in gold - contains recipes from the restaurant opened by the Ottolenghi group in 2011. In the book's intro Ottolenghi describes NOPI as their "grown up restaurant" with "the quality of a serious restaurant but without any of the stuffiness and formality".

His co-writer, NOPI's head chef, Ramael Scully - known simply as Scully - has brought a raft of new flavours to the table including curry leaves, yuzu, lime leaves, glutinous rice flour, pandan leaves, galangal and other staples of Far Eastern cooking.

Born in Malaysia to a Chinese/Indian mother and Malay/Irish father Scully moved to Sydney with his mother and sister when he was eight, eventually attending catering college there. His childhood foodie influences were very different to Ottolenghi's.

"My auntie used to feed me aubergine pickle for breakfast when I was six - I'd take one bite when she was looking and then hide the rest in the rubbish bin," he laughs. "I love it now though," he grins. The pair met at the Islington branch of Ottolenghi, where Scully was doing a trial shift. Ottolenghi writes how wowed he was by Scully's cooking.

"Scully's food also fitted, almost perfectly with the Ottolenghi way. The bold, surprisingly intense flavours that became synonymous with the name, the irreverent blends of ingredients, the curiosity and somewhat restless approach to food (always looking for the next ingredient, a fresh combination or a radically different method): all these were features we unmistakably had in common."

The two share a visible excitement for food which they exude as they discuss the book. It's hard to keep them on track as every new ingredient sets off a stream of foodie digression.

Ottolenghi acknowledges that many of the NOPI recipes are even more complex than his previous books - something bound to lead to social media kvetching but explains they have tried to simplify what were restaurant-worthy dishes.

"The whole idea was that it's a restaurant cook book but we really wanted to make sure that people are able to create it at home - even if it's slightly more of an effort than our earlier books. So it required quite a lot of adjustment. We had to tone down some recipes. We looked at what was on the plate in the restaurant and tried to take out what wasn't absolutely necessary. And we suggested substitutes for those more difficult to source ingredients."

Was he not worried that more complicated recipes have even his fans plutzing?

"I think only some of the recipes are more complicated. Not all of them. I think it applies to maybe 25 or 30 per cent of the recipes. For me it was really important to bring a whole new range of possibilities to people who already like Ottolenghi and cook the food. If someone does do the chicken pastilla for instance, it's a big effort, but the result for people who do make it would be so outstanding that they will go 'wow, that was really worth it!'"

"We're not shy about it because we wanted to bring the NOPI food, which we're really proud of, to the general public, but we did balance it out, so there are a few super simple recipes with three or four ingredients."

Some recipes couldn't be simpler: a whole celeriac rubbed with olive oil and sea salt and roasted for three hours before being served in wedges as a snack to have with drinks. Genius.

"We ate a similar dish with slow roasted vegetables at Noma a few years ago," enthuses Scully.

Ottolenghi is going to need a few easy dishes up his sleeve, with two sons at home under four. He has recently become a father for the second time - Flynn - now eight weeks old. Big brother Max, now three, has taken it in his stride. "He is sweet with Flynn, but has taken it out a bit on us," he admits.

Is Max, the son of a chef, every Jewish parents' dream - the child who eats everything?

"He's pretty good but he's starting to get fussy. Yesterday he loved cucumber and today he doesn't like it. Tomorrow he'll like it again! It's about control. But he never eats raw tomatoes."

As well as a new baby, Ottolenghi has plenty to keep him busy. A baking book is planned; the Spitalfields branch of Ottolenghi (his metaphorical baby) is not yet six months old and he is involved in developing new recipes for Covent Garden fast food outlet, Sesame, as well as writing regular recipe columns and keeping an eye on the rest of the Ottolenghi outlets.

His popularity shows no sign of waning. This is food that takes work, but like all works of art, it's worth it.