My formative experience of Spain was a two-month stint one summer on the InterRail – that great early experiment in European relations – and my introduction to the cuisine was largely conditioned by my limited vocabulary. Nonetheless, there were meals I have never quite forgotten.

At a little pension in the Mallorcan town of Deya, on a terrace smelling of pinewood and sea air, I was served a fragrant rice dish – made in the paella with chicken and peppers, golden and glowing and pungent with saffron – drank a bottle of iced rosado all by myself, and gazed down at the dark sea in a euphoric, alcoholic blur.

Some years later, I was working on a magazine and was sent to Madrid to cover a food fair. That was the moment I became hooked on Spanish culinary culture, and I decided to move to Spain for good. Over the years, I have explored the extremes of the country’s eating habits – from the traditional and rustic to the adventurous and avant-garde – but one of my most exhilarating experiences was taking part in a traditional matanza, the annual pig slaughter.

The anthropologist Marvin Harris has a theory that the human race can be divided into porcophobes and porcophiles: those cultures that flee from the pig as a taboo animal and want nothing to do with it, alive or dead, and those that make pork meat a central plank of their lives. There can’t be much doubt about which side of the fence Spain comes down on. This is a nation whose love of pork in all its forms comes close to worship.

The annual ritual of the pig slaughter is of capital importance in the social history, as well as the culinary history, of Spain. For a rural population living permanently on the cusp of poverty, in which every calorie had to be worked for, the pig killing had an importance difficult to overestimate. This was where people found the proteins and fats their bodies needed for their lives of hard physical labour.

At some point along the historical time line, however, obligation began to be replaced by free will – and this moment is the beginning of the history of gastronomy. The consumer of our time can choose from a range of meats, yet pork will always occupy a special place in Spanish hearts.

On the day of the matanza, I left my house in Extremadura, in the west of the country, in the icy dark of a January morning, and arrived at the Tellez farm, near Caceres, as the sun was coming up reluctantly over the sierra.

The Tellez parents and children were firm friends of mine, but unfamiliar faces loomed up out of the dawn light. The people who stood in the kitchen drinking coffee were villagers who had always helped out at matanzas in return for a daily wage and/or an armful of chorizos. Felipe, the farm hand, was also the pig killer.

Jesus would be the butcher, while his wife, Petri, was the main matancera, responsible for the processing of the meat. In the old days, the expert countrywomen who came to work at matanzas were known as sabias – wise women – and were accorded a great deal of respect: if the matanza was mishandled, a year’s supply of meat might be in jeopardy.

“For three days from now, everything is the matanza. Nothing else matters,” murmured Petri. We were already on matanza time, and the routines and rhythms of normal life had ceased to exist.

“Let’s go kill the pig,” said Felipe, looking like Hollywood’s image of a serial killer, with a black rag tied around his head and a dazed, psycho smile. The killers came out of the house, marching purposefully towards the pigsty, sporting toothy grins and glinting knives, a rifle loaded and ready, and a bucket.

“Make sure you get the blood,” called Antonio, from the house, “or my wife will kill you.”

The next thing I knew, Felipe was right inside the enclosure. He raised the gun and fired; the first pig dropped like a stone, shot clean through the brain. As her husband went for the jugular with his razor-sharp kitchen knife, Petri moved in with the bucket, stirring the bright, hot blood with her hand.

The day’s major task is the deconstruction of the animals and their classification according to body parts and types of meat: lean, gelatinous, fatty and bony. We set to work. Jesus opened the animals like treasure chests, revealing their caverns of pearly-white lard, the steaming architecture of bone and muscle. He leant into them and pulled out a succession of bits and pieces: the liver, a hot, shiny, floppy thing, seeming to cling like an octopus to the butcher’s hand; the long snake of the loin, a metre-long tube of flesh; the heart, kidneys, ribs, lungs.

Toni, another matancera, was now hard at work, trimming the fat off the long, thick tube of the loin, slicing with a practised hand. It would be rubbed with garlic and pimenton and stuffed in a casing, air-cured along with the chorizos, eventually becoming what is known as lomo embuchado.

EXTREMADURA IS cattle country first and foremost, which, in food terms, means three things: fresh meat, cured meat and cheese. From the cerdo iberico, the blackfoot pig that feeds on the acorns of the holm oak plantations, come the region’s serrano hams, chorizos and salchichones. The beef and lamb are of exceptional quality. And the cheeses are some of the very best in Spain. Add to this the honeys of Las Hurdes, the cherries of El Jerte, olive oil, game, wild mushrooms, figs, asparagus and some highly rated wines, and you have a larder pretty well stocked with good things.

There is one local product, though, that eclipses all others. Pimenton de la Vera is a spice produced by drying peppers and grinding them to a powder. It has various gradations of heat, from dulce (sweet) through agridulce (bittersweet) to picante (hot), and gradations of colour, from fiery blood-orange to rust red and ecclesiastical crimson. Together with saffron, pimenton is the quintessential Spanish flavouring. It is certainly the one that most Spanish cooks would not be without.

And it’s pimenton, without a doubt, that constitutes the soul of the matanza. A shiny 2kg bag of it stood on the sideboard in the matanza kitchen at the farm, ready for whatever use we might find for it. The matanceras from the village were at the artesa, the traditional wooden trough, up to the elbows in meat, their arms stained an unfeasible shade of radioactive orange. This would be the filling for the chorizos, flavoured with pimenton and mashed garlic.

There are no recipes – it is all done by eye, then by taste. Nothing is prescribed: the measurements are a lot, less than that, a little, and a handful more.

But the proof of the pudding, or of the chorizo and morcilla, is in the eating. In Spanish, it is called la prueba. A little of the mixture is fried up in a small pan, and tasted for the balance of its seasoning. A little more of this and that, humming and hawing over the various recipes. The prueba is always a rich seam of controversy and argument. This should be saltier, this can take a little bit more black pepper. This needs more pimenton; this has quite enough already.

The sizzling spicy orange mixture is sampled direct from the pan, forks clashing together in the general eagerness to try a mouthful with a slice of bread. Somebody had brought their homemade wine in a two-litre Fanta bottle with the label still on, and we took big swigs from plastic cups besmeared with grease.

But the last, trickiest, most important and most long-winded of all the matanza’s panoply of processes now awaited us. We stood around the table, each with our role to play. While one turned the handle of the big, cast-iron meat grinder, forcing the mix down a spiral and into the skins, another tied the strings in a double knot, another pricked the sausages with a cork stuck with pins, to release the air trapped inside, and a gopher fetched the curling lengths of shiny sausage from the heap on the table and hung them up in ranks from the ceiling. In an hour or two of purposeful stuffing and tying, knotting and pricking, we were finally done.

For the residents of the farm, there was still plenty of work ahead. The chorizos and salchichon turning slowly darker in the air, shrinking and hardening and drying – they would have to be checked on, and smoked a little if the humidity went too high, and sprinkled with pimenton if a crack appeared in the skin.

Walking into the storeroom a month after the matanza, when the roof is garlanded with sausages and filled with a marvellous aroma of the curing meats, one has a moment of surprise at discovering that all that bounty has appeared there, as if by magic.

There would be hams to salt and dry, bags of meat to freeze, lard to clarify, and, the best of all, the Spanish sausages to make. But for the support team, the helpers, the matanza was over for another 12 months. For us, all that was left was the feast to come.

Extracted from A Late Dinner: Discovering the Food of Spain, published by Bloomsbury at £16.99. To buy it for the reduced price of £15.29, with free p&p in the UK, call The Sunday Times BooksFirst on 0870 165 8585

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