Head chef and instructor at Chiva Som's weekly cooking class Paisarn Cheewinsiriwat champions wholesome foods that heal. His students learn how, and more importantly why, to cook food 'low in fat, sugar and salt, high in nutrition and big on taste'.

The food at Chiva-Som International Health Resort, which was recently added to British Airways' first-class menu, reflects its healthy-living philosophy. Forget ducking out for a pizza: the resort is several kilometres from anywhere and only the healthiest cuisine is offered at its two restaurants. 'Chiva-Som is about health; we grow our own organic vegetables, use free-range chickens and employ a family of fishermen to supply us with their daily catch,' runs the blurb. There is no sugar, no fat and definitely no excess boozing: guests are limited to a glass of red or white wine a day. But the regime isn't necessarily punishing, because Paisarn knows how to cook marvellous food without its attendant evils - and daily board includes a Thai massage.

'Oil,' he says 'is the chief assailant.' We are cooking red curry and there isn't a drop in sight, nor is there any coconut milk, the king of ingredients having been substituted for low-fat milk.

'Only use nut or olive oils, and then just a little. Swap the salt for the soya sauce and the sugar for this,' he says, adding an apple concentrate with the consistency and sweetness of honey, simply made by boiling apple juice. 'But it's still essentially sugar, so not too much,' Paisarn tells the students, who have been on the Chiva-Som programme for a week. Cooking is hands-on and the menu includes red beef curry, spicy chicken salad, stir-fried king fish Thai style and cucumber and egg soup.

The Cooking School

Four Seasons, Chiang Mai

It's another glorious morning in the hills of Chiang Mai, with a soft yellow sun filtering through a mass of lush greenery as guests gather for head chef Pitak Srichan's Chef's Choice Cooking Class. Housed in a large air-cooled sala designed by hotel guru Bill Bensley, the school has individual cooking stations at which guests can strut their new skills.

Selecting his favourite five dishes, Pitak is about to take us through a morning filled with chopping, stirring, note taking, mess making and eating. But first things first: for newcomers to the sport, Thai cooking can be a little perilous, which is why the Four Seasons has installed a Buddha House next to the school.

'We give offerings to bless the spirits of our ancestors, grandmother and grandfather,' says Pitak. It's adorned with fresh flowers, fruit, a croissant and bunches of smoking incense sticks. 'Nine in each bunch for luck. Protect you from the kitchen,' says the jovial chef with a giggle.

Then comes a walk through Thai cooking's most intoxicating ingredients: fresh herbs. Ensuring a constant supply of the organic type, the resort grows its own. There are neat rows of lemongrass and kaffir lime bushes, prized for their citrus-scented leaves. 'If you can't pronounce ka, meaning lemongrass in Thai, then have a shot of vodka. Or maybe even two. Really! It makes everything so much easier,' says Pitak.

We pick bunches of sweet basil for the sumptuous roast duck red curry on the 'to cook' menu and then it's into the kitchen. Chef begins each dish with a demonstration, explaining cooking skills, what to substitute hard-to-find ingredients with and how to select the best, while the class sips on fresh lemongrass tea. It's a long day, but we are rewarded with a fabulous roast duck red curry.

Classes run from 7am to 2pm, Monday to Saturday and each day features a different aspect of Thai cuisine: Monday, spicy salads; Tuesday, soups and noodles; Wednesday, freshwater fish; Thursday, curries; Friday, appetisers; Saturday, chef's choice. A trip to the local market and lunch are included.

The Peninsula Academy Cooking School, Bangkok

Etiquette is a big part of Thai dining, as Saipan Loaharanu, director of social affairs and protocol at Bangkok's Peninsula hotel, and a society 'personality', will tell you. No talking with your mouth full? Elbows off the table? No reaching across your companion's plate? All that and more.

We're sitting in the basement kitchen of one of the hotel's restaurants, where guests can graze after a morning spent cooking with the chefs. It's slightly surreal: a lone, elegant table surrounded by carving knives, two silver service waiters and a mountain of food our class prepared after a morning visit to the market.

The heart and appetising soul of the Thai community, the talaat was abuzz with activity; the morning's catch was spread out on tables of ice and fanned with plastic bags by ageing women with few teeth as the city's restaurant buyers hustled for the prize fish. Driving us through an atmosphere thick with pungent herbs, nose-tickling spices, gossipy whispers and raucous bargaining, Saipan had explained the most important part of learning Thai cuisine: finding the plumpest and freshest ingredients available, and buying them daily, so they remained that way.

'Traditionally, eating is a social event. Thai people like to entertain while they feast,' Saipan says. 'To help the party along, we share. Dishes are placed in the middle of the table and everybody takes a spoonful, one dish at a time, before moving on to the next.'

The Thai meal is punctuated with taste and spicy intensity. Gracious and generous hosts, Thais will also make sure their guest is full, usually by ordering too much. 'In Thai culture, rice has a goddess - we pray to the rice and give thanks for the hardship that has gone into producing it,' Saipan says. 'And finish your food. The Goddess of Rice will cry if you don't.'