Few mission statements are as accurate, yet leave so much unsaid, as the one that opens Pierre Koffmann's latest book. "I am a typical French chef," he says at the top of the first page of Classic Koffmann. It's an interesting opening gambit, and a reminder of the extent to which the man embodies French cooking. Even in his 50th year as a chef, and his 46th in London, he has steadfastly refused to fade from relevance, just as his country's cuisine has – even if both are operating in a different landscape now to when French food was the undisputed pillar of fine dining a few decades ago.

There's a good reason for this. After all, French cooking is the foundation upon which modern dining is built. If Spanish, Italian, Japanese, Chinese, Mexican, Peruvian, and any other cuisine that's been exported and elevated to new heights by modern chefs, are the muscles and the organs, French cooking is the skeleton. "Everybody who's a good chef has a French technique," Koffmann says.

And he's absolutely right. He remembers French fine dining's heyday in the 1970s – he helped build the Roux empire in London as a young chef at Le Gavroche and the Waterside Inn in the early 1970s. Almost every job title in an English kitchen is in the French language – commis chef, sous chef, chef de partie. And Koffmann argues that, even if young chefs don't go specifically to France on stages to train, they're learning skills from chefs who did.

"Learning" is an important term when talking about Pierre Koffman. Classic Koffmann is also full of lengthy exaltations from world-leading chefs who learnt from Koffmann at his three-Michelin-starred restaurant La Tante Claire, and also from ones who spent time working under him at his more relaxed restaurant Koffmann's, at the Berkeley Hotel. He ushered in chefs like Gordon Ramsay, Tom Kitchin, Marcus Wareing and Marco Pierre White in the 1990s, but he's still playing a part in the burgeoning careers of young chefs such as Ben Murphy of acclaimed restaurant The Woodford, whom he proclaims is in fact one of his best ever young chefs.

In Classic Koffmann, he chooses not to revisit classic menu items from Tante Claire or Koffmann's, but to give readers an insight into the classic dishes of his youth in Gascony. It's in a way inevitable that, after 50 years in the kitchen, Koffmann's mentality would be one of reflection, rather than progression. But that doesn't mean he's ready to retire – his half-century as a chef is very much 50 years and counting. He talks to us about the milestone, why he came to London, how it's changed, and why his kitchens seem to have produced so many leading chefs.

How does 50 years of cooking feel?

Tiring – 50 years is a long time. But it's the type of job that if you're not passionate, you don't do. It keeps you young, because you spend the day with young people, from 18 to 25. It's good for your brain, and that's one of the reasons, too: if you spend your days with old people, you're going to die fast. I couldn't have done a job in an office, I would have found it very boring. If you enjoy it, you're going to do it until you're 70.

You say "I'm a typical French chef" – What do you mean by that?

Everybody who's a good chef has a French technique – the technique is French. Chinese, maybe, is different, but that's the only one – all the Italians, Spanish who have good food use French technique. So I'm a typical French chef because of the technique. I learned the technique in France. But secondly because I love sauces, and French chefs really love sauces. I only cook French, and I don't cook fusion food. I don't mean fusion food isn't good, but it's not my style.

Is it inevitable that you'd be reflecting at this point in your career?

We still go forward in terms of the cooking. The book is classic cooking that we don't necessarily serve at the restaurant – it's just dishes I like to eat. But we still go forward, because you want to keep your job interesting. If every morning you repeat the same things, it can be robotic. We don't only serve green sardines just because that's what I like to eat at home. Maybe the next book will be like that [a retrospective of classic Koffmann dishes], but we decided to do a book because it's been 50 years, with dishes that I've enjoyed eating over that time.

What brought you to London initially?

When I came to London in 1970, I came for six months. I didn't come to London to cook, because you can find a job everywhere you go if you are a French chef at 17. I came to London to see a rugby game between France and England at Twickenham.

I said I was going to go to England for six months, and after that I wanted to go to Australia and America. I came here, and 46 years later I'm still here. But the food in the 1970s in England was rubbish, it was shit. If you wanted to eat correctly, you had to go to big hotels, like the Ritz or the Savoy, and it was very poor – a plate of smoked trout with horseradish sauce, avocado cocktail was top of the range. It's changed a lot: now you can eat as well as in any big city in the world.

Everyone who's a good chef has a French technique

Do you think it's as important as ever for a chef to do a stage in France?

When you're a young chef, you've got to move. It's very important. Not specifically in a three-star restaurant – although you've got to do that if you can – but any stage, moving, when you're young, up to the age of 28.

When I was in France I never stayed more than seven months in one job. When you work there, you've got your chopping board and your knife. But if you work with blinkers, you need to remove your blinkers and see what's happening here, and there, and you learn much faster. It was only when I came here in the 1970s that I stayed at Le Gavroche for two years, and The Waterside Inn from 1972-1977, until I opened La Tante Claire.

Gordon Ramsay, Tom Kitchen, even the top American three-starred chefs have worked in France. So maybe you don't need to go especially to France, but if you go to work with Gordon, or at The French Laundry, you will learn the French technique. If you are a painter, first you have to make the colour. If you're a chef, it's the same – you've got to learn to sweat the shallot before you make the sauce, how much brandy you put in a sauce, how long you let it reduce for. Once you know all that, you can do what you like.

Read all about it

You can get a unique glimpse into Pierre Koffmann's childhood in Gascony through the recipes in his new book, Classic Koffmann. Released to mark his 50th year as a chef, it's a collection of dishes that have influenced the way he's cooked over the course of his distinguished career.

Classic Koffmann by Pierre Koffmann (Jacqui Small, 2016)

How does it feel to have trained so many important chefs?

Sometimes people say that I had a lot of famous chefs coming into my kitchen, but they were not famous when they came. Gordon Ramsay, Marco Pierre White, Tom Kitchin – people ask "How can you make so many good chefs?" I didn't make them – they wanted to be famous. They came to work for me to have a good CV and to learn something, but their success was because they wanted to be good chefs; it wasn't for me to take them by the hand.

Do you remember the first chef you trained opening their own restaurant?

Bruno Loubet was. And Bruno, when he left, opened a restaurant on Fulham Road, had fantastic write-ups, and was doing very well. Everybody who opens a restaurant and does well, I'm happy. I'm never jealous. When you've got competition, it pushes you to do better. Now we eat on the other side of London. Lyle's, Portland, Clove Club, Pidgin – they're only young people, and it's fantastic to see the young people doing well.

What can you teach young chefs aside from pure technique?

You've got to give them some freedom. I had a young chef, Ben Murphy, who came to me and stayed for three years. Ben was something special – he always liked to do different things, to improve things. I love young chefs who want to do their own things. Maybe when I was younger, not as much, but I like people who do a dish, and just try to improve it. Ben Murphy is my best example of a brilliant chef, at the moment.

What's on the agenda for you in the next five to ten years?

At 68, I don't know. In 2003, when I was 55, they said "you've got to retire one day", and I took very good insurance, so I went travelling for a year, and when I came back I started to get bored, so I came back to work.

Actors never retire, or painters, or sculptors. As long as the legs are working, it's OK. To be honest, if I retire in the next two years, I'd be dead. I'd do nothing else but cooking. It's the only thing I know.