Celeb chef Prue Leith on her latest cookbook and her recipe for eternal youth

SA-born Prue Leith walked into the room fresh from hosting a cookery class at the respected Prue Leith Chefs School in Centurion, Gauteng, of which she is patron.

"Gosh these students know so much," she says rather proudly, as she sank into a comfy chair, cup of coffee in hand. She was dressed in the colourful style for which she has become known as a judge on The Great British Bake Off.  The famed chef, ex-restaurateur, cookbook author, novelist and TV celebrity was wearing an emerald green and turquoise outfit.

Ever the entrepreneur, with many fingers in many pies, Leith loves business. It goes beyond food, her recent collaboration with eyewear company Ronit Furst being a case in point. A range of exclusive cookware she collaborated on with British kitchenware company Lakeland will soon be available in the UK.

Ever-youthful Leith, who was just days away from her 80th birthday when we met, oozed youthfulness, energy and vitality.

Can this be attributed to the man in her life?

"I think he has a lot to do with it," she said of partner John Playfair, who she described in a recent interview as her "toy boy, hes only 72". They've been together for close to a decade.

"I'm very lucky because John is very funny. He's really a very nice guy and makes me laugh," she said.

Man aside, I pressed Leith to share her recipe for eternal youth. "It's good food, lots of sleep and love well," she said.

Leith has recently launched a new cookbook, The Vegetarian Kitchen, in collaboration with her niece, pastry chef and vegetarian Peta Leith.

It has an eye-catching drawing of a large tomato on the cover and is colourful and appealing with many tempting ideas that don't use a mountain of ingredients. Some detractors have said the women are cashing in on the growing vegetarian trend sweeping the world.

"Not so," said Leith, pointing out that she wrote a vegetarian cookbook 25 years ago.

"At the time I wanted to call it The Vegetarian Kitchen, but the publishers said I couldn't because it wouldn't sell," she said.

To prove her point, she said that for many years at her Michelin-starred restaurant in London "we carried a full vegetarian menu alongside the main menu".

On meat matters, "I'm not very strident about [eating meat]. If you lecture people it doesn't work. The message is eat less and buy a better-quality meat."

Her and niece Peta's more gentle approach is apparent in the cookbook, which is filled with lots of enticing ideas, even for meat lovers.

"If we all eat much less meat it will be good for the planet, kinder to animals, do a lot of good for our health, and it's cheaper, so we should do it," said Leith.