We beat the snow. Our oil is in. And an odd thing has happened to us: we've learned how to do something. I can't remember the last time I actually learned a skill. Possibly it was wiring a plug. Fanning an avocado? Is that a skill? But now if someone were to turn to me and ask (as might happen, perhaps, in a Post Office queue), "do you know how to make your own olive oil?" I could answer: "yes, madam, indeed I do". And from under my coat I would bring a litre bottle of our second batch and hold it to the light. "Look at the hue!" I would say. "Have you ever seen such a … "

"Cashier number 4, please."

Oh God, I've become an olive bore. It's what comes from thinking about nothing else for a month. Angsting over maggots, flapping over quotas, weighing bucket after bucket on bathroom scales, picking olives, processing olives, dreaming about olives. Loving olives, hating olives ...



Our losses to frost were heavy - it claimed dozens of boughs on the shadier terraces, turning the fruits a soft and sickly brown. Our other great enemy is the worm. There are two distinct pests: one white and wiggly, the other a small, tan-coloured pupa the size of a rice grain. We hate them both. When we've gone to the lagar to book ourselves a slot, we've examined some of the sacks sitting ready to be pressed and seen hundreds of the damned things slicking around the inside of the plastic. Most lagars give the olives a wash before crushing, but that'll only get rid of the maggots that have left their holes. Most will be sitting quietly inside as the screws tighten, wondering why their home has become suddenly smaller. So this is one thing we've learned: the olive oil you've just drizzled on your couscous? It's worm oil. The worms, I suppose, are 99% olive, but that doesn't get away from the fact: olive oil is 1% worm. Probably more if it's organic.

Frost-affected rotten olives. Photograph: Hannah Borno

Our olives have been relatively maggot free, but the later you pick, the more pestilent your crop. We became perfectionists, rolling each olive across our palms, checking for rot, mould, holes … becoming paranoid lest a single flawed

fruit contaminate our haul – fussing out every leaf and twig, having been told, grimly, by the lady in the agricultural shop that not a single stalk should reach the press.

Progress was slow. We were hunched around a log fire, on tiny wooden stools, working with kitchen sieves and cereal bowls, tossing stalks and maggots and substandard olives into the flames. We went slightly mad. Briefly, chaotically, our house turned into a 19th century sorting factory, with leaves everywhere, twigs everywhere, buckets and sacks and trays and bowls and boxes of olives EVERYWHERE. Everything was olive stained: our hands, our nets, our clothes, the floorboards. We thought about manufacturing a linen dye from olive juice. We thought about giving up. For a brief time, I could measure my life in olive tubs. Every tub was 10kg, four tubs to fill a sack, then onto the next. And the next. And the next.

The first pressing, at Pedrógão Pequeno, we sorted completely by hand. We loaded the car at 5.30am in pitch darkness having booked the first slot of the day. Although once at the lagar, the first slot mysteriously became the second slot, which became the fifth slot, and slipped again. Various trucks, vans and tractors slid in ahead of us for reasons we were far from fathoming. We shuffled about, smiling at the operatives, then were suddenly summoned to the weighing machine. 216 kilos, well above the 150 minimum. The conveyor belts rumbled into life, the sacks were split, and away into the bowels of the beast went our precious haul.

Sacks of olives ready for the press. Photograph: Hannah Borno

This was a modern press. State of the art, EU regulation, all gleaming pipes and digital displays. It took half an hour for our oil to emerge, hot and yellow from the centrifuge. 21 litres, so almost exactly a litre from every 10 kilos, (with every 10 kilos costing a euro to press). Is this good? We have no idea. We drove back, proud but weary, to tear some bread and taste our blessed oil. The first harvest from the quinta, the finest olive oil, doubtless, that the Iberian peninsula has ever produced.

It was insipid.

There's no getting away from it. Insipid. It tasted like oil. Warm oil. Warm oil that had taken us hours and days and weeks and half our sanity to produce. "Good cooking oil" I suggested to Hannah. She nodded, and made a suggestion of her own: "we could burn it in lamps."

We thought about our oil. We thought what might have gone wrong. It was a modern press and came highly recommended. Our olives were as clean and twigless as ever a batch has been. Then we realised: it was the colour. Our sacks were blacker than anyone else's. Our olives were overripe. We'd taken only the ripest from the trees, and set aside the green for pickling.

Now, everyone will tell you something different about the optimum green-black split. The lady in the agricultural shop who'd sold us our olive combs, who'd warned us against a single stalk tainting our oil, was insistent: the olives must be 100% black. Online, the commonest ratio seems to be 3 black to 1 green. I think her advice was bad.

The green olives give the oil its peppery taste – this seems to be the consensus. So, a few things changed for our second pressing. We upped the number of greens, relaxed about stalks, and we crumbled and bought a sorting machine. Never have 277 euros been better spent. We tore through our backlog. What was taking us an hour suddenly took us a quarter.

The second attempt at pressing was at Mosteiro, a small village half an hour away. It was a traditional, steam-powered press, crushing the olives between raffia mats on century-old hydraulic screws. Or so we were told. When we got there we could see the magnificent old press, rusting in pieces on the forecourt, piles of rush mats rotting in the rain. They'd just had a refit. So much for comparing new with old.

The second batch of oil emerges from the press. Photograph: Hannah Borno

But still, it was a smaller, more intimate affair. Every bit as baffling as the first, but friendlier, as countless other people were ushered in ahead of us. It was past midnight, and everyone had gone home happy with their oil, except for one man who had brought a basket of chicken wings and a box of wine to make an evening of it. He liked the look of our olives, and gave us some chicken. At last, just when we were giving up hope, a young fellow leapt into a forklift truck, and our olives were loaded onto the scales. 572kg. A cool half tonne. And from this 76 litres was squeezed. A better ratio, but what about the oil? The fellow with the chicken wings nodded approvingly as it trickled out into our plastic churn: "muito bom, muito bom." He was drunk, but it didn't seem like he was blowing smoke up our buckets.

The proof was in the tasting. A glass each of hot oil. A sniff, a sip, and a warm, peppery sigh of relief. It was absolutely gorgeous. Really, properly delicious. 76 litres of green and gutsy joy. Noticeably greener than the first batch, and incalculably better. I'm not just saying this because we worked so hard to bring it into being, but it's the best olive oil I've ever tasted. Every time I taste it, days later, I think, "muito bom". This is our olive oil for the year. So much for labelling it "single estate" and hawking it at a farmer's market. This is for personal use.

Tasting the second batch. Photograph: Hannah Borno

Driving around the countryside, we've seen half of Portugal up ladders, up trees, huffing nets in the rain and bumping around on top of olive sacks behind a tractor. I'm very aware that we've only just dipped the corner of our bread into a tradition that runs deep through the valleys of Portugal, and stains the lives of the people. If a little knowledge is a dangerous thing, then we are the deadliest olive farmers in all of Castelo Branco. We have been schooled (to primary school level) in the ancient alchemy of the harvest, witnessed and engaged in the heaving transformation of sack upon sack of black and mottled olives into the glorious green gold of the oil. We have stood triumphant over half a tonne of plucked prey, torn the fruitstained smocks from our chests and howled our knowledge at the harvest moon: "This thing of nature I acknowledge mine!" Then picked up our smocks and gone inside because it's freezing.

So that was our harvest. Blooded by the juice of a hundred boot-squashed olives, we are no longer quite the ingénues we once were. Our techniques – for emptying nets, spotting maggots, clipping treetops – all these have sharpened. And yet, the pruning of an olive tree is a fine art to which our crude hackings can only aspire, I've just discovered that many people round here trample the olives (black and green), let them half ferment and pour off the juice before taking them to the press. The knack of hefting a wet olive sack still eludes me, and the inner workings of the olive press remain a mystery of Delphic proportions. Next year we'll take chicken wings and some wine. Maybe that gets you bumped up the list.