We meet at his Stephen's Green restaurant, Thornton's, and he arrives looking as though he has just stepped out of the shower, his short, curly hair still wet and clinging to the side of his head. He wears a grey, woollen jumper and jeans and has a small stud in one ear. He is unexpectedly slim and looks as though he might be about to climb a mountain in Connemara if he weren't the owner and head chef of a two-star Michelin restaurant.

No sooner are we through the glass door than Thornton is making coffee and suggesting croissants. The interview is off to a very good start. Through the glass porthole into the kitchen I can see white hats bobbing up and down between the steel shelves and hear music mumbling softly in the background. "We're here from seven in the morning and we don't normally finish before 2am, " he says bluntly, as though marking out the difference between his team and the mere mortals who inhabit the rest of the world.

He sets down the tray carrying our coffee cups I can see his hands are scarred by knives and hot pans. No sooner have I produced my polite list of questions than his mobile phone rings.

"What are the scallops like? What size are they? Hmmm."

He mumbles and then makes a series of thoughtful noises down the phone to his caller, places his order and then hangs up with a coarse "Bye, bye, bye, Ciao".

We are here to discuss Thornton's book, Food For Life, a collection of photographs taken by Thornton himself and all the proceeds of which will go towards helping to fund research into acute meningococcal disease. Ten years ago Kevin and his wife Muriel's son, Conor, was cured of the disease using the treatment known as Protein C . . . all the money raised by the sale of his book will aid further research.

The book showcases a collection of Thornton's photographs of food, animals and wildlife and includes a few images of Conor, now aged 11, one in particular captures him fishing for trout in Lough Derg.

Thornton writes of Conor's life-threatening illness and miraculous recovery in the foreword of the book. His account is both frightening and inspirational because he and his wife Muriel could have lost their son had it not been for the determination of the doctors and nurses who attended him at Temple Street Children's Hospital in Dublin.

"Ever since my son was ill I have wanted to repay them even though of course I could never repay them. I had always wanted to do a book but not recipes or anything as cliched as that so I approached a number of publishers but in the end I decided to do it myself. You see, that's the trouble with me, I'm a control freak."

He describes the lengths to which he went to produce the book; he took a prototype to the Frankfurt International Book Fare a number of years ago and succeeded in attracting the attention of a number of publishers in the United States. After a while, it became clear that they too, wanted a book of recipes, of which Thornton would only be credited with a proportion of the publishing rights.

"They would have charged me for reproducing any of my own recipes so naturally, I said 'F**k that. I'll do it myself '.

"It's pornography, " he says of the book. "Food is life and these photographs are an account of our life." The photographs are indeed vibrant but as for pornography, I'm not so sure. There are a number of wonderfully detailed images of fauna and a series of pictures chronicling the skinning and preparation of a hare.

When I suggest that some people might find these images harrowing, he almost leaps out of his chair, "How could they?

This is the process. I am showing a natural process. If people are going to eat they should know how the food gets to their plate. Are you a veggie?"

He has a pronounced Carlow accent, which on occasion is difficult to understand and I think he takes a certain amount of pleasure in baffling his interviewer.

"It's the accent you see, " he says proudly. "Might take you a while to get the hang of it."

Thornton describes himself as a lucky person, "I was in a diving accident but I survived. My son had a life-threatening disease and he recovered. I am a lucky person."

Despite his sunny outlook, his face is tired and looks as though it is worn by more than just long nights in a hot kitchen. Conor is not the Thornton's only son. As a young couple, Kevin and Muriel gave birth to a boy, Edward, who was later adopted. It is only in recent years that they have succeeded in making contact with him. He does not explain why Edward was adopted but refers to the event as when "my son was taken from me".

"He has two kids. We found him in England, it was difficult but Muriel is a brilliant detective, she would make a great PI. It's quite simple if you know how . . . we went to the adoption board and as it turned out we dealt with the same people that we had been with when Edward went through the adoption process. I don't believe adoption is good for anybody.

"Everybody suffers. Of course, people can be made happy by adoption but the fact is that everybody is still hurt. The parents are hurt, the biological parents are hurt, the adoptees are hurt. Deep down there is a pain. I'm not saying I go around crying all the time but they are hurt, everybody is hurt."

I ask him if finding Edward and building a relationship with him has eased this pain and he pauses momentarily before shaking his head. "No, not really. The thing is I remember at the time it was very painful and thinking that when I met him the pain would be over . . . but it's not, it's a new type of pain."

Shortly after their reunion with Edward, Kevin decided the only way he could express how he felt towards him was through food so he organised a 14-course dinner for the entire family.

"I just knew the best way to express my emotions was through food and so I planned this dinner and cooked lots of the things I knew he liked and well, it was great."

Thornton is as frank about the adoption of his eldest son as he about restaurant critics (he's not too keen on them) and I don't imagine he's afraid of being rude at times either although I suspect it it is largely due to his eagerness to achieve everything in a very short space of time. At one point, he tries to make light of his determination and suggests that if he were a rich man he wouldn't be slaving away in the kitchen but moments later he contradicts himself by declaring that if he didn't love his work he wouldn't do it. Despite such throw-away comments, however, it is clear that he is an incredibly driven individual who prides himself on the quality of his work.

"There should never be a price on quality, " he says in response to my question on the production cost of the book. "If the quality is amazing, the price tag will come along accordingly. For instance, could you put a price on that book?

The actual cost? I have no idea and I'm afraid to add it up;

I know if I added it all up in terms of time and labour costs it would be well over the selling price and if you were to try and calculate the emotional endeavour . . . well, that is priceless."

I repeat a quote from him that I had read in a previously published interview where he was reported as saying "Food is theatre" and he shrugs and says matter-of-factly, "That is bullshit. I didn't say 'food is theatre'. I said what we do here is theatre! The restaurant is theatre in the sense that we open up and we have to act and perform and just like actors on a stage we don't get a second chance. The kitchen is like an orchestra, everyone is performing and they all have a job to do and we all have to hit the note at the right time and if something goes wrong then it all goes wrong. Basically, we are trying to seduce the customer from the moment they stick their nose inside the door to the second they take their arse out of it."

He was born in Carlow and brought up in a rural community. He describes an almost idyllic childhood with his many brothers and sisters and stresses the importance food has played throughout his entire life.

"Food is life. Here in Ireland, we think we have a food culture because we have a few trendy farmers' markets but we don't at all. When I was growing up, we took the food out of the ground and cooked it. I killed chickens with my father for dinner . . . that is a food culture. Nowadays in Ireland, people just eat for the sake of eating and I don't think Irish people eat well, they mostly eat shit. One of the biggest problems about food is the convenience of it. People pretend they care where it comes from but that really only stretches as far as the packaging . . . as long as it comes in a nice little bag with 'Finest' written on it, but that isn't real. Skinning a hare may be brutal but that is life and we should be aware of it. People should know where their food comes from because food is life."

Food For Life, by Kevin Thornton is published by Thornton's, priced 100. It is available from Thornton's Restaurant, Fitzwilliam Hotel, St Stephen's Green. All proceeds go to aid research into acute meningococcal disease