Rayner was sitting in the Sirena, one of Moscow’s top and over-the-top restaurants. It is, says Rayner, a strange place to eat. The floors are made of glass, there are sturgeon and carp swimming beneath the feet of the oligarchs perusing the menu.

“The crazy thing is that what you are served is essentially gefilte fish.” And although this particular gefilte fish is dressed up as “carp in the Jewish style” and elaborately presented in a Michelin-starred kind of a way, it suddenly hit Rayner with a jolt.

“Had history taken a different turn and my family had stayed in Russia, this would not have been a part of my culinary heritage which I visited nostalgically every now and then — this would have just have been dinner.”

While Ashkenazi comfort food plays a role in Rayner’s life (although he has always despised gefilte fish), it is fair to say that it does not play a dominant role. Rayner is obsessed by fine restaurant food. His trip to Russia was part of a globe-trotting gastronomic journey, detailed in his new book, The Man Who Ate The World, in which he ate at top restaurants in Las Vegas, Moscow, Dubai, Tokyo, New York and Paris.

It gave him the chance to explore his own fascination with this kind of dining as well as examine his own attitudes to eating.

“I became aware that there was this new breed of luxury restaurants and the truth is that while I get to eat all over Britain, there are a whole bunch other places that I didn’t have an excuse to go to — but I wanted to know what they were like. I also felt this was an opportunity to investigate the global economy through its restaurants. Each city is chosen not because it is a good place for me to eat dinner, because no one would want to read about that, but as a way into another story.”

Hence the chapter on Moscow which allowed Rayner to flex his reporting muscles as well as his gastronomic sensibilities, although ultimately he could not wait to leave.

“It’s a sinister, dark and worrying place. The whole chapter is about the end of Communism and the rise of the mafia. Then there’s the personal thing. My shiksah wife has an uncertain relationship with Ashkenazi food. If truth be told, she thinks it’s mostly drek. But if, like me, you are a cultural Jew who draws upon intellectual rather than faith-based traditions, there’s not much left other than salt beef. Coming face to face with that through this journey has been an eye-opener.”

So what of the other destinations? Rayner rates Tokyo as the world’s top food destination (“over there, Gordon Ramsay didn’t even warrant a Michelin star”), Russian food was “miserable in every way”, and London was, well, a bit thin. In fact, he says he only included the city because it is his home town — the book includes meaty segments about Rayner’s own background and attitude to food.

And it emerges that the watershed moment of Rayner’s childhood involved (and observant readers might like to avert their eyes) snails. Rayner was 11-years-old when he ate alone in a restaurant for the first time. He was on a skiing trip in Switzerland and was homesick. His way of dealing with the problem was to walk into a posh restaurant and order the escargots, which his mother, agony aunt Claire Rayner, would serve him as a treat.

“It seemed like an obvious thing to do and I gained succour from it. I recall that if I was nervous about going in, it was only about whether they would agree to serve me the snails rather than a whole meal.”

Snails apart, Rayner’s childhood was dominated by food — much of it Jewish. “My parents were both children of the Depression. Food was scarce for them, but they wanted us to live a life of plenty, and we did.

“My mum wasn’t religious but she could cook all the Jewish stuff. She has an uneasy relationship with her Jewishness. I’m probably more relaxed about it than she is. Despite her uneasiness she was completely cognisant of the Jewish cooking tradition. She could make chopped liver, she could make gefilte fish and, for some reason, before we had our Christmas lunch of turkey we always had chopped liver on matzah.”

Rayner’s eclectic upbringing was not confined to food. Claire was, in the 1970s, one of Britain’s most recognisable faces and the family’s lifestyle reflected her fame. There were dinners aplenty at Joe Allen’s in Covent Garden and there were many encounters with celebrities. None of this phased the young Rayner. “At the time you know no different, so it didn’t strike me as odd until later that I had a famous parent.”

However, his mother’s fame did motivate Rayner in his teenage years. “I realised that if I wanted to be a journalist and avoid the charge of nepotism I was going to have to do something radical. Actually, I still got that charge even after I had won Young Journalist of the Year, which pissed me off a bit.”

His career is now such that he need not be wary of the comparisons with his mother. He had 12 years as a serious news journalist before taking on the job as the Observer’s restaurant critic and starting to write novels (so far there have been three). So why was he so keen to write about food? “I had been eating out in high-end restaurants since my 20s. My wife indulged me although she thought the whole scene was a little silly. I had become a bit of a nerd on the subject. Look at me , I’m a North-London Jew — we like to eat.”

He is not the only Jew writing about restaurants. There is Giles Coren at The Times, Matthew Norman at The Guardian, Michael Winner at The Sunday Times. So what is it about Jews writing about restaurants? “Well, we’re big eaters, we’re smart-arses and we like sitting around tables. I’ve sat with Giles and Matthew in restaurants and played the game of who can come up with the smartest line. I can even remember Giles texting me from table to table when we were reviewing the same restaurant. We are very competitive.”

If there is a downside to his job it is that it makes it hard for him to maintain his physique. After writing The Man Who Ate the World, he engaged in a week-long Super Size Me-style exercise in Paris where he ate at top restaurants every night to see what it did to his body. By the end of the book the Michelin stars had turned him into Michelin man — he tipped the scales at nearly 21 st. He now works out six times a week.

He says: “I have a taste for pork belly and crème brulee — things which are guaranteed to put on weight.” He pauses. “Considering this is the JC we maybe we should replace the pork belly with roast lamb.”

The Man Who Ate The World is published by Headline Review at £16.99