Aldo Zilli wants a siesta. He's tired. He's hot. We've been drinking wine for an hour and his head is hurting and now we're whizzing along the poppy-lined roads to Pescara. There is a fish auction we have to go to. It's important. That's what Zilli says. Very important. Half an hour later we're looking at baby monkfish. 'It's illegal to fish them so young in Britain,' says Zilli. We all look at the huge dusty pink crayfish still wriggling their legs. Aldo Zilli starts laughing.

Next door, at the auction, grumpy fishermen who have been up all night sell crates of lobster and inky octopus to local restaurant owners. Zilli peers into the crates and then explains what he might cook with the contents; his spaghetti lobster perhaps, or chargrilled squid with rocket and lemon.

All the fish has made Zilli hungry and before long we go to Taverna 58, an old restaurant in the historic centre of Pescara. Zilli is here to source food for his London restaurants, and looking at the menu he is as excitable as a young boy. His businessman friend Antonio Sutti, acting as tour guide, tells the waiter that Zilli is a famous London chef and within minutes a wooden board with a taster of all the local specialities arrives. Bruschetta with sausage, seasoned pecorino with sliced pear and honey, raw salt cod. A hot bowl of polenta bread, fagioli and 'wild leaves from the field'. The extra virgin olive oil is a deep green and tastes almost good enough to consume on its own.

As he eats, Zilli talks about his late mother's cooking. The bruschetta with sausage reminds him of his after-school snacks. Pouring a glass of local red wine, he says his ambition has always been food-related. 'A lot of Italians dream about buying their first Ferrari. Mine was always to buy a wood-burning oven which I only achieved last year in Zilli Fish Too.' He smiles. 'I was so excited that I cooked everything in it for the first month.'

Aldo Zilli has been in love with food for as long as he can remember. As a child growing up in Abruzzo, a quietly beautiful and largely undiscovered area south-east of Umbria and directly east of Rome, Zilli remembers being given the sort of food which is now the staple of modern Italian cooking. 'My father was a farmer and we had a garden overflowing with fruit and vegetables, so we were pretty self-sufficient: when I came home from school, my mum would give me bits of ciabatta bread toasted on the fire with a couple of slices of fresh tomatoes, some basil and olive oil. Perhaps the odd bit of rocket too.'

One of nine children, Zilli maintains that his mother fed the family the healthiest of foods; no fast food snacks, no crisps or chocolate bars. When he was 13, she taught him how to cook gnocchi, his favourite dish. Inspired by helping his mother in the kitchen in his teens, Zilli attended catering college in Pescara, left Italy to travel round Europe and arrived in London at the end of the Seventies in his early twenties.

After running Il Siciliano in Soho, he opened Signor Zilli in Dean Street in 1987. Fifteen years on, he has filled his mantelpiece with awards (including Best Italian Restaurant in 1996), he has become a regular fixture on television and his restaurants have effortlessly attracted A-list celebrities. In the past 18 months he has expanded his empire; after the success of Soho's Zilli Fish and Zilli Notting Hill, he went on to open Zilli Fish Too in Covent Garden and Zilli Cafe in Soho. He has become celebrated for creating simple, fresh food, from pasta to fish to pizzas - one of his signature dishes is a mouth-watering spaghetti and lobster.

Yet it is only recently that Aldo Zilli has looked to his native Abruzzo to source food and wine. Last year, while filming Wish You Were Here around the area, he realised what he was missing. Not only stunning scenery ranging from the cobalt blue sea to the mountainous national parks (this is apparently the only place in Europe where you can ski and see the sea), but also first-class produce cultivated by locals fiercely proud of the region's micro-climates. He also missed his family; he had lost his mother, father and a brother, but he was still close to the remaining siblings.

These days, Zilli returns to Abruzzo every few months to sample mozzarella, pecorino, wine, extra virgin olive oil, not to mention De Cecco's pasta, which you can find in your local supermarket and which is quite possibly the best there is. 'Some produce has already made its way to England, like the De Cecco pasta. I used to just go and buy my stuff from the Italian distributors in London, but it's an amazing experience sourcing food and wine for myself. I've met so many different people. I want to bring the quality of Abruzzo produce to my restaurants; I want to step up the quality and drop the price.'

So, at the end of April, we travel to Abruzzo with Aldo Zilli for a few days to sample the freshest of mozzarellas and meet some of these characters. Even after 23 years in exile, Zilli is still very Italian. But along the way he has picked up a bit of a Cockney accent, so when he likes something it's not 'magnifico' but 'wicked'. He clearly enjoys being a celebrity chef - and why shouldn't he? It's a great lifestyle after years of hard labour in the kitchen - but he has not forgotten about the food itself.

We are driven out into the Abruzzo countryside by Sutti, who is acting as chief advisor, helping Zilli find the best local produce. Sutti was born in Piacenza but makes it clear where his heart is now. He asks my favourite place in Italy. I tell him around Florence and Siena and he slows the car; I am free to leave. He smiles but the pride is visible in his eyes.

The Abruzzi don't take kindly to our continued love affair with Tuscany, but even Sutti has to concede that tourism in Abruzzo is a new thing - until Ryanair began flying directly to Pescara recently, the easiest way to reach the city was a two- hour drive from Rome.

We arrive at Marramiero, a family-run vineyard with hazy views of the Adriatic in one direction and Gran Sasso, a breathtaking 3,000m snow-tipped mountain, in the other. In the cellar we sip a dozen wines and a sophisticated but crisp Brut spumante. Zilli is excited; he has not only found a potential new table white and red (Dama Trebbiano D'Abruzzo and Dama Montepulciano D'Abruzzo are both pretty special and each costs less than £2) but is also contemplating replacing champagne with the Brut. 'We have a traffic of around 1,000 people a day in my restaurants and I want everyone to have the opportunity of tasting Abruzzo wines, whether they be table wines or this wicked Brut.' We emerge from the cellar light-headed and giggly, blinking hard in the warm afternoon sun.

The next day is hectic. First stop is the Mercato Coperto, Pescara's main fruit and vegetable market, open Monday to Saturday 7am to 2pm. Misshapen lemons as big as grapefruits; huge, twisty peppers, some red and others almost black; baby artichokes; leafy green sticks which are not exotic celery but palm hearts. And tomatoes to die for, vine and beef and plum, all with a heady fragrance that floats above their wooden boxes.

When Zilli asks a stallholder if the strawberries are local, she smiles and nods vigorously. 'Of course they are. We grow them in greenhouses.' The local pride here is fierce and Zilli explains that the Abruzzi like to think of themselves as pretty self-sufficient, with access to the freshest fish alongside high quality meats, cheeses and wines.

As we wander around, Zilli can't stop smiling. 'If I lived here, I'd cook every day. Without a doubt.' He pauses and looks at a stall with a dozen different types of mushroom. 'I just want to get my hob out and cook right here and now. This is the most amazing place isn't it? It's so inspirational because I keep seeing all these ingredients I'd forgotten about, like fresh palm hearts. There's a guy from Covent Garden market who imports Italian fruit and vegetables. I'm going to get him on the case on Monday morning so I can start inventing new dishes straight away.'

Long after we've left the market, as we speed down the coast towards San Vito Marina, Zilli is still lost in thought. 'The vegetables are weird shapes and sizes and even colours; have you ever seen a black pepper before? Italian markets really are where it's at because everything is seasonal and it's mostly organic.'

Driving south along the coast to see the fishermen's old-fashioned wooden huts on the edge of the unfeasibly blue Adriatic, we stop off to see the house where the Mussolini-era poet Gabriele D'Annunzio used to write poems celebrating Abruzzo. A little further down the coast we admire the rickety wooden fishermen's huts when a man in his seventies eating an orange starts chatting. He has fished all his adult life and he feels safe here; he goes out on his boat all night and leaves his car keys in the ignition. He points to the house on the hill where he was born and where he still lives. Holding up his orange, he explains that he planted some orange seeds 50 years ago and now he has wild trees. I ask if his life has been hard. He smiles and shakes his head. 'How can life be hard when it is so enjoyable?'

The fisherman mentions that he grows his own organic olive oil and Zilli is thrilled; perhaps he could use it in his restaurants. He likes the romantic idea of meeting some guy on the beach and doing business with him, providing the oil is of a high enough standard. He takes his number and promises to be in touch. Before we leave, the fisherman takes Zilli by the arm. 'This may not be the best place in the world, but it's calm and it's genuine.' Zilli, lost in nostalgia, nods and smiles.

The climax to the trip is to be a meal at Zilli's old family house, where one of his older brothers and sister-in-law now live with their two daughters. But first there is a sheep to adopt up in the mountains. The coastal scenery rapidly gives way to vast expanses of trees and within 20 minutes we are surrounded by sheer mountains with spring snow decorating their summits. We pass signs saying 'Attenti ai Lupi' (beware of the wolves). 'You are about to see paradise,' announces Zilli in a whisper.

Here in the truly unspoilt and dramatically scenic Parco Nazionale d'Abruzzo lives Annunzio, who makes the best organic pecorino cheese I have ever tasted. For £150 a year, anyone can adopt a sheep and in return be sent four kilos of pecorino, wild honey, jams and some woollen jumpers. Zilli hands over the money and is introduced to his sheep, a two-year-old called Neve, who is surrounded by bouncy week-old lambs.

Just the other week, Annunzio turned CNN away; he was too busy tending his lambs. He knows he has to accept agriturismo, in which farmers either sell their produce to the public or rent out rooms, but he wishes life could be the same as it was 100 years ago. He shows us the white puppies with woolly coats whose job it is to protect the sheep from wolves and explains how they live outside with only the strongest surviving.

Annunzio is hoping to sell his cheese to Zilli - the last time Aldo paid a visit, a local restaurant was overflowing with young, mature and seasoned pecorino - because, quite simply, he needs the money. Zilli's enthusiasm for the pecorino is as genuine as that for the wine he tasted a few days earlier, but as a successful businessman, he knows he can ill afford to be sentimental. 'There is no point in buying cheap stuff or pretending to be interested in produce that isn't of the highest quality. But Antonio has done a fantastic job in showing me the best producers - as you can tell by Annunzio's pecorino.'

And so to the family meal in Alba Adriatica, the small seaside town north of Pescara where Zilli was brought up. Zilli's sister-in-law Marisa has been preparing for days. She has been endlessly phoning Zilli as we've been touring Abruzzo, asking him if he wants this or that dish. Zilli laughs each time and wonders just how much food we shall be given. Italian hospitality is legendary, but Marisa takes it to another level.

Sitting around a long table with Zilli's brother Giacomo, his two daughters and another brother, Guido, we are presented with a three-hour spectacular. The fish is simple but fresh - anchovies with lemon, squid with tomatoes and basil, whole baby monkfish and calamari lightly fried only in flour and salt - it is immediately obvious where Zilli's inspiration comes from.

Alongside the fish, we are served seafood risotto and an artichoke and mushroom timbale - to call it a vegetarian lasagne would be a crime, given its status as one of the best dishes anyone round the table had ever tasted, with its fresh, tangy artichoke hearts and succulent, almost meaty mushrooms. It is a recipe that has been in the family for generations.

Aldo jokes that there is enough food to feed 50 people. This is not a meal but a feast. Giacomo serves his selection of home-made alcohol: white wine, a sweet after-dinner liqueur called Limoncello followed by the fiery, intoxicating grappa. The brothers reminisce about old times, laughing as they talk and pausing only to eat. Every now and again they stand up and hug each other.

In the car on the way back to the hotel, everyone is sleepy but content. 'Did you hear my niece Sandra say that she'd passed the timbale recipe onto all her friends and now they are all in awe of her mum for being such an amazing cook? How nice is that? If my daughter did that with one of my recipes, I'd be so proud. But she's 17 and living in London. In big cities it's harder to keep such traditions going.'

Zilli is hoping to use some of his mother's and sister-in-law's recipes in his new cookbooks. 'The problem is that the recipes have never been written down. I've been having fights with Marisa to get them out of her. She lived with my mother for the longest, so she knows the most. She still gets up at 5am to make her fresh tomato sauce and her duck ragu.' Aldo Zilli sits back and pats his stomach. 'I just wish I could get Marisa to cook for me in London. That really would be wicked.'

· To order Aldo Zilli's new book My Italian Food for Friends or Zilli's Fish Cookbook for £14.99 each (rrp £16.99), both plus p&p, call the Observer book service on 0870 066 7989.

· Magic of Italy reservations: 08700 270500; brochures 08705 462442. www.magictravelgroup.co.uk

· Sheep adoption: Zilli head office on 020 7437 4867

Tagliatelle al Ragu di Salsiccia

For an excellent tasting sauce for this dish of pasta with sausages, be sure to use fresh ones from a butcher or a good Italian deli. The sauce will keep for 3-4 days in the refrigerator, so you can make more than you need and then enjoy the remainder another day with a different pasta. If possible, make your own pasta - it's very rewarding and tastes fantastic.

Serves 4

Preparation time: 15 minutes
Cooking time: 1 hour 20 minutes

350g fresh spinach or egg tagliatelle
60ml freshly grated pecorino or Parmesan cheese

For the sauce:
8 fresh Italian pork and garlic sausages
15ml olive oil
1 onion, peeled and finely chopped
1 carrot, peeled and finely chopped
1 celery stick, finely chopped
225ml vegetable stock
2 flat mushrooms, chopped
1 bunch of fresh thyme, tough stalks removed
1x800g can plum tomatoes
salt and freshly ground black pepper
50g butter

Preheat the oven to 200°C, 400°F, gas mark 6. Place the sausages on a baking tray and cook in the oven for 10 minutes.

Heat the oil in a large saucepan, add the onion, carrot and celery and pour in the stock. Cook for 5 minutes. Chop the sausages and add to the pan together with the chopped mushrooms. Cook for a further 5 minutes. Stir in the thyme leaves and tomatoes with their juice. Season with salt and freshly ground black pepper. Cover and cook for 1 hour until the sauce is thick, stirring occasionally.

During the final 10 minutes of the sauce's cooking time, cook the pasta in a large pan of boiling salted water for 5-8 minutes, or according to the instructions on the packet, until al dente. Drain and transfer to a large pasta bowl. Stir the butter into the sauce, then pour over the pasta. Sprinkle with the cheese and toss to mix. Serve immediately.