"I always get obsessed with things," says head chef Ramael Scully, explaining how he recently spent £100 on eBay buying 1.5kg of the rare spice, Grains of Paradise.

"It's like drugs!" shouts his friend, collaborator and boss, Yotam Ottolenghi - but then, if you're as consumed by food and flavour as these two, addiction is inevitable.

What makes Ottolenghi food - which you'll know if you've ever eaten at an Ottolenghi restaurant, bought an Ottolenghi cookbook or read an Ottolenghi recipe in the Israeli chef's Guardian column - is the sheer number of ingredients involved.

"Haha, we're not Italian cooks. It's not like four great ingredients put on a plate," says the 46-year-old restaurateur with a laugh. "Of course, a fresh tomato with olive oil is a great thing, but that's definitely not the way I grew up - otherwise it wouldn't be Ottolenghi."

He explains it wouldn't be NOPI or Scully food either - and this is the pair's current project, a restaurant standard cookbook based on the food served at NOPI, Ottolenghi's renowned eatery in London's Soho.

But this is a restaurant book with a twist, do not expect a coffee table slab, to be looked at and not touched. It should be daubed with spice and oil.

"I thought it was going to be a very chef-y cook book, so I was really excited," says Scully wryly. "Then [Yotam] was like, 'No, Scully, we're doing the restaurant food we do here for home cooks'. I thought, 'Yeah, it'll be a walk in the park' - it was the hardest thing I ever did!"

Jerusalem-born Ottolenghi first met Scully - who grew up in Australia but has Chinese, Indian, Malay and Irish blood - in 2005, hiring him as chef de partie.

"It's not a typical story where someone grows under someone else's roof," explains Ottolenghi. "Scully came in with his own style already. Obviously, it's evolved and changed over the years, but I haven't taught him how to cook. It's a partnership."

"Yotam is a man of words," says Scully graciously. "I had all these ideas and crazy things on the plate and Yotam's like, 'No, no, no, too much Scully, calm down'. But he knew I always had the flavour part, I just couldn't control it on the plate. And that built between us all these years. Sometimes, now, I tell him he's got too much on the plate!"

This was the trickiest aspect of putting together the NOPI cookbook: lopping off at least some of the ingredients Scully would ordinarily use in the restaurant kitchen.

Top picks include the twice-cooked chicken, the Urid Dhal cod ("A very satisfying dish for entertaining," promises Ottolenghi) and the vine leaf pie (a "piece of heaven", apparently), and they can't help spiralling into off-the-cuff cooking tips ("If you're making tzatziki - put burnt butter in it," encourages Scully).

Unable to live without "a bucket of Maldon salt", vinegars, tahini, preserved lemons, coriander and cumin seeds, cardamom, saffron and turmeric, their food may be complicated, but if Ottolenghi's three-year-old son, Max, is anything to go by, anyone can tuck into NOPI food.

"I used to feed Yotam's kid a lot of offal," says Scully, grinning.

"He ate a lot of complicated stuff before he could talk, he was really happy to try all these things, now he's asserting his personality!" chips in Ottolenghi. "He likes to eat grown-up food, sometimes he drinks coffee - black coffee! I'm like, 'Max are you sure you like black coffee?' 'Oh no, no, no I love it!' I don't think our food is good for very young kids, but as of six or seven or eight, it's brilliant."

Scully disagrees: "Any kid will love popcorn ice cream!"

Scully became a chef to travel the world, and got a lot of practise cooking for his sister while their mum, a nurse, did split shifts, but he originally had plans to become a marine biologist or fireman. "I surfed for so many years, I always loved the ocean. And I liked fire - I used to burn a lot of stuff."

"You do a lot of burning still!" says Ottolenghi, who, in a world without food, would concentrate all his efforts on writing. "Food without stories is normally quite boring," he notes.

For their own next chapters, Ottolenghi has a book on pastry planned, and Scully?

"Scully will eventually go out on his own," says his boss, fiercely. "He does deserve his own restaurant. That is definitely happening."

To get a taste of NOPI at home, try one - or all three - of these...

:: TOMATOES WITH WASABI MASCARPONE AND PINE NUTS

(Serves 6)

250g mascarpone

1tbsp wasabi paste

10g chives, chopped

10g tarragon, chopped

1 spring onion, finely sliced

2 banana shallots, sliced widthways

2tbsp sweet sherry vinegar

1tbsp olive oil

1kg mixed tomatoes, cut into slices and wedges 1cm thick

20g pine nuts, toasted

5g mixed basil leaves

Coarse sea salt and black pepper

Place the mascarpone, wasabi, chives, tarragon and spring onion in a bowl with half a teaspoon of salt and a grind of black pepper. Mix well and keep in the fridge until needed.

Mix the shallots with the sweet vinegar, oil and half a teaspoon of salt in a separate bowl. Pop this in the fridge too.

To serve, divide the mascarpone between the plates and spread to form a thin layer. Place the tomatoes on top, followed by the pickled shallots. Sprinkle with the pine nuts, scatter over the basil leaves and season with a third of a teaspoon of salt and a grind of black pepper.

:: LAMB RUMP WITH VANILLA-BRAISED CHICORY AND SORREL PESTO

(Serves 4)

25g sprigs of rosemary, stems discarded and leaves picked

15g sprigs of thyme, stems discarded and leaves picked

2 extra thyme sprigs

3 garlic cloves, peeled

75ml olive oil

1kg lamb rump, fat trimmed and scored

30g unsalted butter

1 vanilla pod, halved and seeds scraped

2 large white chicory, quartered lengthways

1tbsp caster sugar

1tsp coriander seeds

50ml chicken stock

50ml dry white wine

Coarse sea salt and black pepper

To make the Sorrel Pesto:

40g sorrel leaves

15g mint leaves

Zest of 1/2 lemon

15g capers, rinsed

7 anchovies

1 garlic clove, crushed

1 medium red chilli, de-seeded and diced

1tbsp olive oil

Blitz the rosemary and thyme leaves and garlic in a food processor with two tablespoons of oil to form a rough dry paste. Rub all over the lamb and leave in the fridge to marinate overnight. Remove from fridge half an hour before cooking, to return to room temperature.

Blitz all the pesto ingredients with half a teaspoon of salt and a grind of black pepper, to form a smooth paste. Set aside.

Saute half the butter on a medium-high heat and add one and a half teaspoons of olive oil, along with the vanilla pod and seeds, when it starts to foam. Sprinkle the cut sides of the chicory evenly with the sugar and half a teaspoon of salt. Place them in the pan, cut-side down. Cook for four minutes, turning once, until the chicory has caramelized and turned golden-brown. Lower the heat to medium, add the thyme sprigs, coriander seeds, chicken stock, wine and a grind of black pepper. Bring to a simmer and cook gently for two minutes, until the chicory is tender. Remove the chicory, discard the liquid and vanilla pod, and set aside somewhere warm until ready to serve.

Preheat the oven to 220C/gas mark 7. Wipe off and discard the marinade, before sprinkling one tablespoon of salt and plenty of freshly ground black pepper evenly all over the meat. Place a medium ovenproof frying pan on a medium-high heat with one tablespoon of oil and, when the pan is hot, add the lamb rump. Cook for four to five minutes, until golden-brown, then turn over. Add the remaining butter and cook for another minute, until the butter starts to foam. Transfer the pan to the oven and cook for a final five to six minutes, for medium-rare, longer if you want it well done. Remove from the oven and rest for two-three minutes before slicing into 1cm thick pieces.

Serve with the pesto and chicory on top, drizzled with the remaining olive oil.

:: STRAWBERRY AND ROSE MESS

(Serves 6)

160g mascarpone

270g creme fraiche

15g icing sugar, sifted

1 and a 1/4tsp rose water

40g caster sugar

2tbsp pomegranate molasses

1tsp sumac (a lemony tasting spice, available in all good supermarkets)

200g strawberries, hulled and chopped into 2cm pieces

60g meringues broken roughly into 2cm pieces

Seeds of 1 medium pomegranate

2tsp dried rose petals (optional)

To make the strawberry sorbet:

40g caster sugar

40g icing sugar

30g liquid glucose

200g strawberries, hulled and blitzed into a puree

Place the sorbet ingredients in a small saucepan with 60ml of water. Warm through on a low heat, stirring so that the sugar and glucose dissolve. Remove from the heat and set aside until completely cool, before transferring to an ice-cream maker. Churn for 20 minutes, until firm but not completely set. Place in a container and freeze until needed.

Whisk together the mascarpone and creme fraiche until smooth. Add the icing sugar and rose water and continue to whisk, just until combined. Keep in the fridge until required.

Mix the caster sugar with 40ml of boiling water and stir until the sugar dissolves. Add the pomegranate molasses and sumac, stir to combine and set aside.

To serve, divide the strawberries between four bowls or glasses, followed by the meringue, rose water cream and half the sumac syrup. Top with the pomegranate seeds and a dessert spoon of sorbet. Finish with the remaining syrup and the rose petals.

:: NOPI: The Cookbook by Yotam Ottolenghi and Ramael Scully is published by Ebury Press, priced £28. Photography by Jonathan Lovekin. Available now

THREE OF THE BEST... For cooking with spice

:: Marble Pestle & Mortar, £49, Oliver Bonas

If you want to grind your spices in style, this white marble offering from Oliver Bonas should do the trick. Your kitchen will be fragrantly filled with the smell of perfectly crushed spices in no time.

:: Mini Mason Jar, £4.99, HomeSense

Sometimes you just need a whole lot more cayenne, jerk seasoning or turmeric than those mini bottles of spice from the supermarket allow. Decant into a mason jar for easier access. Alternatively, use this to store preserved lemons, a la Ottolenghi.

:: Amorim Alma Gemea - Spice Rack, £45, Amara

Pop your salt, pepper and mixed herbs into brand new homes. These bright earthenware pots are easy to carry when it comes to seasoning at the dinner table too.