I have loved Africa for many years, except at meal times. So when we rented a house in Kenya during the winter, I had great expectations of the weather and the landscape, but none of what we would eat. I told my wife and friends who were coming to stay that they should think of food as petrol, not pleasure.

Then we met Mungai, our cook for five weeks, and began to sample his fare. From the first souffle, through the egg mousse to the spinach pancakes, we realised that we were in the hands of an artist. Around mid-morning, people began to hang about the kitchen door, to gain some hint of what the maestro was planning for lunch. Towards 1pm, restless figures began to queue at the trough, fearful of missing something. For the first time in many years of visiting Africa, I found myself getting as excited about dinner as about the wildlife.

I should set the scene. Mungai plies his skillet amid an impeccably equipped modern kitchen with a bottled gas cooker and electricity supplied by generator, in a corrugated iron-roofed farmhouse in the midst of the northern Kenya bush, where zebras graze within sight of the dining room. The nearest shop - delightfully named the Settlers' Stores - is two hours away by Land Rover up a shocking track on which 20mph is good going. It proved easiest to order supplies from a supermarket in Nairobi and get them flown into the dirt airstrip by one of the little puddle-jumping planes, when somebody arrived to stay.

Mungai is a Kikuyu, maybe 35 years old, who became a farm worker 10 years ago at Nick and Heather Day's ranch, Kamogi, on the Laikipia Plateau, where we were staying. Heather, an uncommonly effective woman who hails from County Down, noticed Mungai because he could read and write, quite rare accomplishments in northern Kenya. She taught him to cook. A spell as assistant in the kitchen of a nearby Italian ranch owner refined his exceptional skills at Italian dishes.

Today, he lives in one of the modest farm huts just beyond the vegetable garden, the latter a trifle bruised by a night visit from a couple of elephants. Mungai is one of five English-speakers among 45 people working on the ranch, which enables him to digest Jamie Oliver, The River Cafe Cookbook, the divine Nigella and The Very Best Asian Recipes. All these works stand on the kitchen shelf. He himself is a quiet, grave, sometimes mildly melancholy figure who doesn't say a lot, but produces food that bears the stamp of exceptional talent.

Pasta is his best thing, much of it home-made. My wife was amazed to pass the kitchen one morning and find Mungai creating individual hand-made ravioli which, at lunchtime, proved miniature masterpieces. Duck with honey, mushrooms and noodles is perhaps his supreme effort. By the halfway mark of our stay, I took to wandering down to the stables to count the remaining ducks scratching around in the straw and ensure there was no danger of a supply crisis before we left.

It would be deceitful to say that absolutely everything Mungai produced was perfect. Like every cook, he is dependent on his raw materials. The vegetable garden proved amazingly prolific. Meat, on the other hand, is tough: your average Kenyan cow or sheep has a hard life before it meets its maker and it shows.

There are, however, plenty of splendid alternatives. The local lakes are heavily populated with crayfish. We developed a routine of riding out on the horses early in the morning for a bush breakfast beside one of the dams. Industrial quantities of eggs and bacon were fried on site by Mungai. Afterwards we trooped down to the water's edge while he threw in a net adorned with a lump of rotten meat. We waited patiently for five minutes. Then he lifted his bait, usually crawling with crayfish.

We rode home and suffered an impatient wait of three or four hours until the crayfish appeared with pasta in a cream sauce for lunch. I would have been perfectly happy to eat Mungai's crayfish and pasta every day, but there were allegations that I was inciting genocide in the lakes.

Part of the reality of living in the bush is that there are no little brasseries up the road for a change of scene and to give the staff a break. We ate Mungai's rations at every meal. Breakfast was irresistible, with especially delicious toast made from Mungai's own bread. He also makes his own muesli, of which my wife brought home a huge jar, having stuffed herself with it every morning at Kamogi. At lunchtime, however, it seemed essential to restrict ourselves to salad and cheese (there is a remarkably good cheese manufacturer creating Kenyan Gouda outside Nairobi), in order to be able to do justice to the full works come dinner.

There was one crisis, about mid-term, when the farm manager cheerfully announced the bad news that he thought Mungai had typhoid; while assuring us of the good news was that he would be fine to work next day. This prompted mild hysterics among our more delicate guests, who suddenly felt far from home and fearful for their digestive systems.

Fortunately Mungai didn't have typhoid and his assistant Reuben maintained an amazingly high standard of catering through the three days the great man was off games. But it gave us a nasty turn to sample life without this wizard of the wok, while he was getting over his bug.

For us middle-class types, accustomed to doing our own dirty work in the kitchen, it was a novel sensation to have absolutely everything done by other people. Sometimes, one feels a tiny twitch of frustrated desire to drift into the kitchen and whip up a can of baked beans to eat in front of the telly. There were a few pangs for the simple life, and the odd attack of satiety, when confronted with yet another culinary orgy. Yet the mood passed, and we were soon enthusiastically tucking in again. We had difficulty getting some of our guests to leave, so hooked did they become on sun, wildlife and the catering. We lowered our voices when speaking of Mungai, out of reverence for a master. And by the way, don't even bother to ask. The place is taken. We have already rented Mungai for five weeks next winter, and the house comes with him.

· Hugh Fearnley-Whittingstall returns next month