Food and Drink: Just add water for flavour - A few dried Italian porcini, cheaper than fresh wild ceps and much easier to find, will animate the most humble pasta or meat dish

I lugged a drying machine back with me from Switzerland last summer - for drying foodstuffs, not clothes. It was cumbersome on the plane, but I considered it worth the effort - though I was a little disappointed to see the same model on sale in this country a few weeks later, and for only a fiver more.

I had been inspired by the Lerchi family, with whom we'd spent a good deal of time while filming in the Swiss mountains. They used a Dorrex (pronounced perilously like a certain rubber article, much to our childish delight) to dry fruit, herbs and vegetables. As a leaving present, the Lerchis gave us a generous bag of dried wild mushrooms. I was so taken with the idea of drying my own wild mushrooms that I had to buy exactly the same machine.

I imagined myself bringing back sacks of mushrooms from autumnal walks, eating some fresh, and drying the rest for the winter. Fine in theory, but my few walks yielded zilch in the way of fungal bounty. I've dried some apples, pears and plums - extremely good they are, too - but not a single mushroom.

Instead, I have continued to do what I've always done: buy mushrooms in small packets from the Italian deli down the road. In Italian, our caps, or penny buns, and the French ceps are called porcini (piglets); and their botanical name is Boletus edulis. But whatever you wish to call them, they are one of the most highly rated of all wild mushrooms.

They are also the most widely available dried mushroom and a bargain buy. While you may seem to paying a fortune for a tiny amount, they cost much less than most other sorts of dried mushroom - except the ones you've picked and dried yourself - and the power they carry is tremendous: enough to animate plenty of other cheaper ingredients. They cost less, mushroom for mushroom, than fresh ceps from some chic greengrocer (you are unlikely to find fresh ones anywhere unchic), and they are available all year round.

It must be said, however, that there are dried porcini and dried porcini. Most delis carry the cheaper sort, which are excellent. They come neatly wrapped in 1/2 oz (15g) or 1oz (30g) packages, stapled in rows to a piece of cardboard, like a packet of peanuts at the pub.

The glitzy food stores in this country, and the ones in Italy aimed at knowing tourists, sell the prime pieces of dried porcini - larger, pale tan, elegantly displayed in clear boxes or pretty baskets - at a correspondingly prime price.

These are the dried mushrooms to buy as presents for your nearest and dearest, or that someone you want to impress. They may be the bees' knees of porcini, but I've never been totally convinced that they are as massively superior as their presentation suggests.

Though dried porcini may be short on substance, they have the most exuberant, full, earthy taste. Combine these mushrooms with ordinary cultivated ones, and you have the best of both worlds.

Try adding them to a mushroom soup, or a sauce, or just sauteeing them with button mushrooms in butter, with a little garlic, some parsley and a final slug of white wine. If you happen to be partial to beef stroganoff, you can really beef it up with a tiddly packet of porcini. Mushroom risotto is better than ever with a shot of dried porcini. And on their own, they make a good addition to stuffings for poultry.

However you choose to use them, the first step is always the same. To rehydrate: place the dried porcini in a small bowl and cover with hot water. Leave for at least 20 minutes to soak and soften. Pick the pieces out carefully and pat dry on kitchen paper or a clean tea towel. Leave the soaking water to settle for five minutes or so; by this time, the grit from the mushrooms will have sunk to the bottom. Carefully pour off this wonderfully flavoured water, leaving the grit behind; or strain the water through a muslin-lined sieve. Even if you are not using the water in the recipe, don't throw it out. Think of it as mushroom stock, and freeze it. Then it can be used in a sauce or soup, or to make a mushroom gravy.

Instead of water, you can soak the dried porcini in sherry or

wine. I prefer a medium-sweet or dry sherry for this purpose. Use it cold, and leave the mushrooms to soak for longer (at least half an hour).

Tagliatelle with porcini sauce

One of the easiest and most appetising ways of mixing dried and fresh mushrooms is in a creamy sauce for pasta. The sauce can be made in advance and reheated. For a bit more oomph, soak the porcini in sherry rather than water.

Serves 4

Ingredients: 1/2 oz (15g) dried porcini, soaked

1 onion, chopped

1 clove garlic, finely chopped

2oz (55g) butter

12oz (340g) button mushrooms, finely chopped

1/4 pint (150ml) double cream

squeeze of lemon juice

2tbs chopped parsley

salt, pepper

freshly grated nutmeg

12oz-1lb (340-450g) tagliatelle

Preparation: Chop the porcini and strain and reserve their soaking water. Cook onion and garlic in butter until soft, but not browned. Add porcini and their soaking water, and simmer until water in evaporated. Add chopped fresh mushrooms, salt and pepper, cover pan and stew for a further 20 minutes.

Remove lid and simmer until liquid has almost all evaporated. Add cream and nutmeg to mushroom sauce, and simmer together for 5 minutes, until thickened. Draw off the heat and stir in lemon juice and parsley. Taste and adjust seasoning.

Meanwhile, cook tagliatelle in boiling salted water until al dente: fresh pasta should take just a few minutes; dried may take up to 10 minutes. Drain well, and serve with the mushroom sauce poured over it.

Baked halibut with porcini crust

In this recipe the mushrooms are mixed with breadcrumbs to make a crisp crust on top of pieces of halibut (if you can't get halibut, use the freshest cod).

Serves 4

Ingredients: 1/2 oz (15g) dried porcini, soaked

1 1/2 oz (45g) fine white or brown breadcrumbs

leaves of 1 large sprig of thyme, chopped

3tbs olive oil

4 halibut steaks, weighing 6-8oz (170-225g) each

salt and pepper

Preparation: Season the halibut with salt and pepper. Drain the porcini and strain the soaking liquid. Chop the porcini finely and mix with the breadcrumbs, thyme, salt and pepper. Stir in the olive oil, mixing well to make sure each crumb has soaked up its fair share. Press half the mixture on to one side of each steak, covering the surface thickly. Lay the steaks, crust upward, in an oiled, shallow, oven-proof dish. Spoon about 4tbs of the soaking liquid around them.

Roast at 200C/400F/gas mark 6 for about 20 minutes, until the crust has browned and the fish is cooked through.

Roast chicken with porcini

This is such a good way of lifting ordinary roast chicken right out of the ordinary, and of keeping it moist while it cooks. Butter, flavoured with porcini, thyme and lemon is smeared between the flesh and the skin before the chicken goes into the oven. And that's all there is to it.

Serves 4-6

Ingredients: 1/2 oz (15g) porcini, soaked

2tbs chopped parsley

1 clove garlic, roughly chopped

finely grated zest 1 lemon

juice of 1/2 lemon

2oz (55g) butter, softened

1 small onion, quartered

1 free-range chicken

salt and pepper

Preparation: Drain the porcini and pat dry. Save the soaking water (strained first) for another dish, or for making gravy. Chop porcini, parsley, garlic and lemon zest together very finely. Mash with the lemon juice, butter, salt and pepper.

Gently wiggle your fingers under the skin of the chicken, easing it away from the flesh on the breast and upper thighs without pulling it right off.

Now - and I find this easiest with fingers, but you may prefer to use a spoon as well or instead - push the flavoured butter between skin and flesh, smearing it as evenly as possible. Put the onion quarters inside the cavity of the chicken.

Weigh the chicken and calculate the roasting time. Allow 15 mins per pound (450g), plus an extra 10 minutes. Roast at 220C/425F/gas mark 7, basting frequently with its own juices. If it threatens to burn, cover with foil.