Still as much of a celebrity magnet as it was when it first opened, Nobu, famed for its sushi, has spread from a single LA restaurant to a worldwide phenomenon, these days with bedrooms to extend the experience of fabulousness. This summer, a second Nobu Hotel will open in London, in Portman Square, to join its sister hotel in rather more edgy Shoreditch and two standalone Nobu restaurants, both in Mayfair. How has this American import, which brought the now ubiquitous “black cod with miso” dish to Britain in the late 1990s, managed to evade the vagaries of foodie fashion and become a solid success story? The answer probably lies in its celebrity connection — but one in the boardroom rather than the dining room.

When, not so long ago, I spend time with the Hollywood actor Robert De Niro — co-founder of the chain — I find him gentle, kind, empathic, funny. Initially one thinks “actor decides to be restaurateur and hotelier in twilight years because actor needs back-up as they’re not getting the roles”. But De Niro is getting the roles. His much lauded film The Irishman is up for 10 Oscars next weekend. He was also rather brilliant in Joker , with Joaquin Phoenix — another awards big contender. He’s happy to multitask as an actor and Nobu impresario. De Niro has a very distinctive look. It’s somewhere between angry, tired and curious. He’s wearing a very lived-in jacket, his shirt is crumpled. His new black suede trainers look at odds, his hair is grey but full and longish. When he stands up, you try to work out: is he tall? Officially 5ft 10in, somehow he transcends height. He’s a man who is passionate — his passions also seem to transcend size. He’s a man of few words, but his words are usually either impactful or funny. The eyes, which can twinkle very disarmingly, narrow when he speaks to you, so you’re not sure if he is scrutinising your soul or about to fall asleep. But he’s much more approachable than you imagine, friendly even.

How come someone of such impeccable Italian heritage likes Japanese food so much? De Niro laughs. “I’ve got Italian, German and English all in me.” His mother was of Dutch-French-German- English ancestry, his father Irish-Italian. The story of his side hustle as a restaurateur and hotelier began about 25 years ago, when De Niro was a regular at a small but cool Japanese restaurant in Los Angeles called Matsuhisa, whose chef and patron was Nobu Matsuhisa, running his first place in the city. The Japan-born chef had honed his speciality, black cod marinated in miso (see recipe, page 47), in Alaska. Before that he was in South America. De Niro has worked out that I have trouble saying the name of Nobu’s first restaurant, which is actually Nobu’s last name — Matsuhisa. He tries to teach it to me over and over again as if I am a baby learning to speak. When he’s satisfied, I tell him the first time I went to Matsuhisa, Kelly Osbourne took me. She said it was a family restaurant that she’d grown up in.

“Well, I was there one night with a British friend, Roland Joffé [director of The Mission], and I told Nobu, ‘If you ever want to open a restaurant in New York, let me know.’ And a few years later he said, ‘I’m ready.’” One taste of Nobu’s signature dish was all it took. “I had the cod and that told me right away, this guy is really special,” De Niro says. Is he good at making instant assessments of people? He nods.

“I like him. He’s low-key and I knew that there is no way this restaurant would not have worked in New York.” De Niro brought in his friend Meir Teper, a financier. I catch up with both of them, along with Matsuhisa, at the Nobu Hotel in Las Vegas. Teper, a former fashion impresario and film producer, is now in his seventies, but he’s still lithe and elegant from an early career as a dancer in his native Israel. I wonder, did he meet De Niro on a movie? Teper explains. “We were friends first. I worked with him on movies a couple of times, but I met Bob through another producer friend.”

Was it an instant feeling of a kindred spirit? “It was, actually. We talked, but not that much. Because he had a good feel about me. More than I had about him because he’s the big star. One day he called and said, ‘Do you want to come with me to Deauville film festival in France?’ I said sure. He was there to promote [the 1987 film] The Untouchables. Paramount got me a ticket. I met him in London and we hung out together. Then we flew to Deauville, and after that every time he went on a trip he called me. He felt comfortable travelling with me. We became friends and we started travelling together. If he was going out on the road for promo or location-scouting he liked me to join him. We like the same things. We like looking at things and we like hotels.” Together they could escape the crowds and the media. A comfortable hotel room and a comfortable friend was exactly what De Niro wanted.

“I remember one time we went to London,” says Teper. “We always would travel under different names, but somehow someone at British Airways told the press and when we landed the paparazzi were everywhere. We were in a limo with the paparazzi all following us. Bob says, ‘Don’t go to the hotel. Let’s go to this other hotel that has an entrance in the front and we’ll come out the back and get a black cab to our hotel,’ which was the Savoy. We lost the paparazzi — it was like a movie, but it was real life.” You can see why they get on. They’re both men of few words who, when they warm up, don’t shut up. They like talking about details: food and bed linen, places and cultures. They can go on for ever about such things and they can also be quiet with one another.

In what sounds like a movie title, De Niro, Teper and Nobu Matsuhisa are called The Stakeholders. Stakeholder is where it’s at, rather than CEO or controller; they’ve put in the money, the time, the skill. Teper says: “Bob brought me to Matsuhisa, saying, ‘I found a nice Japanese restaurant. We should have dinner there.’ It was a very small restaurant with 30 seats — and Nobu was talking to every table and cooking for them. We all became friends.” He liked De Niro’s idea to bring Nobu to New York. “The idea was to invest and hopefully get my money back,” Teper explains.

“I used to travel to New York a lot and I wanted to have a place to have food there as good as we have in Beverly Hills, and to meet friends.” Never underestimate that old Cheers bar factor. A place you can call your own. Where everybody knows your name. Or at least your sushi preference. Teper continues. “After New York, we were so successful people started saying, ‘Can we have Nobu London? Can we have Nobu Vegas?’ Nobu’s a chef, Robert De Niro’s an actor. I was the only business person in the group. I understood how to negotiate, how to make the deal.” Gradually Teper’s interests in film and fashion disappeared. “I’m so busy with Nobu and I put so much time into it, everything else has gone away.” De Niro takes pleasure in just observing a room. The image that stays with me is Teper and De Niro sitting in the rooftop penthouse suite of the Nobu Hotel in Vegas. It’s the hotel’s fifth birthday party. Caviar and Moët are being served; Nobu chefs in white coats are making sushi and grilling things while leggy girls serve champagne and lychee martinis.

None of the stakeholders even looks at them. Teper and De Niro watch everything as if it’s on a screen, as if they’re in a different movie of their own. This party is for all the casino high rollers. There is no VIP area, no silver cord, yet the stakeholders keep to themselves. De Niro looks content, approachable, but no one does approach him. How does he balance the Nobu empire with his acting career?

“I’m not doing what they do,” he says, referring to his business partners. “I’m here when they need me. We always ask each other for input. I’m front and centre when needed.” He doesn’t do the deals like Teper does, he is the metaphor for the brand. They need him to be still acting. “These days, we have meetings on set if it’s not a tough day. Sometimes I’m waiting around a lot, so we sit in my camper. Sometimes you need less distraction. It depends. Sometimes you need to get your mind off something. It’s a welcome distraction. ”De Niro and his chef, meanwhile, are very different, yet seem to relax each other, almost like a Morecambe and Wise Christmas show. “I cook from my heart,” Nobu says. “Why does everyone like their mother’s food? Because the mother cooks for the kids with heart. I don’t ever want to forget to cook with heart, with passion. It’s about making people happy. Success never makes people happy.” Was his mother a good cook? “Oh yes. She would always have ask what I wanted to eat tonight, tomorrow? Always with heart.” I wonder if this is the secret. I ask De Niro if his mother was a good cook? “Not great,” he replies.

If he was a Nobu dish, what would he be? “I might be the artichoke salad.”

I was rather hoping to be the artichoke salad myself. Soft and creamy on the inside, crispy on the out.

“OK,” he says without a fight. “I guess I’d be a big fish. The cod.”

”The black cod with the sweet misoon the side that you don’t discover straight away?”

“Yeah.”