Don't tell them we told you but...

After years of making restaurants social hot spots, the cognoscenti have taken to patronising unnamed, underground eateries.

The underground restaurant scene offers a curious combination of professional service and intimacy.

I probably shouldn't tell you this, but the hottest restaurant trend for 2009 is actually a secret. In major cities across the world, regular restaurant-goers have got bored of discussing which places have been sprinkled with Michelin stars. They're talking about a new breed of hush-hush, word-of-mouth restaurants (or rather, word-of-Facebook) hidden behind private, unmarked doors. These unadvertised and unregulated secret restaurants have been springing up from Los Angeles to Hong Kong, and have proved a surprising hit in a year where more established dining places have been feeling the pinch. Feeding a public that is weary of overpriced posing spots and craving a bit of novelty, these clandestine restaurants offer both a bite to eat and a bit of mild social adventure, luring their punters to undisclosed locations to dine cheek by jowl with people they've never met before.

In case whispers about these underground eateries haven't yet reached your ears, this is how the concept works. Secret restaurants usually let the public know about them quietly, putting out feelers through blogs and networking sites such as Facebook and Twitter, steadily building up a following based mainly on friend-to-friend recommendations. Once you've tracked down a restaurant's blog or network profile, you then send an e-mail requesting a booking. Only after your reservation has been confirmed are you given an address to come to. What happens next varies wildly from place to place - the great pleasure of secret restaurants is that you never know exactly what you'll find when you get there.

Spacious Victorian sitting rooms, sleek minimalist bachelor pads, riverside boathouses and warehouses fitted up with theatre sets and ladders are just some of the venues that have been kitted up and opened as secret restaurants this year. The food, meanwhile, can range from affordable and wholesomely vegetarian to rather fancy and experimental, though one common feature is that most restaurants offer their customers a single set meal rather than a menu.

While there has been a huge buzz over secret restaurants in the world's major cities this year, it has to be admitted that the phenomenon isn't entirely new. What is new is the wildfire spread of the concept across the West. London, which had no secret restaurants until this year, now has 11 establishments, ranging from modest spots hidden away in public housing to lavish lofts offering haute cuisine with haute prices to match. There are now 14 secret establishments in the San Francisco Bay Area, while New York has a phenomenal 24. While mainland Europe hasn't gone quite so berserk for the trend, there are secret restaurants in Berlin, Dusseldorf, Prague, Amsterdam, Copenhagen, Vienna, and at least six in Paris - and with the trend spreading to Australia and Hong Kong, this isn't a purely Atlantic phenomenon. So why has the trend suddenly taken off?

The answer can perhaps be found in the phrase that can strike both fear and boredom into the most hardened newspaper reader: the credit crunch. With pay packets and expense accounts getting leaner, slick, expensive corporate restaurants are not just seeing their bookings going down, they're starting to look a little, well 2007-ish in a world where ostentatious bling has fallen from grace. It seems people are looking for a more homespun, less bluntly commercial experience.

There's also the voyeuristic pleasure of poking a discreet eye around somebody else's house and the raw excitement of discovery. While this curious combination of professional service and intimacy is great for anyone who is jaded with their city's usual dining options, secret restaurants have also proved a big hit with travellers. Out-of-towners too often end up dining in the sort of bland, overpriced restaurants that invariably congregate around tourist honeypots, or in the so-so antiseptic dining rooms attached to major hotels. Secret restaurants, on the other hand, give you access to someone's private home, giving you a close-up glimpse of local life that would otherwise be hard to come by, and take you to parts of town that visitors normally overlook.

But what about the food? How can someone cooking up a glorified dinner party possibly compete with a professional chef? Well, the truth is that they don't necessarily try. Secret restaurateurs are a very diverse group of people. They range from seriously rated professional chefs who are keeping their skills sharp in a gap between restaurant projects to passionate home cooks who feel like upping their game with a bit of semi-professional catering. This potluck variety means that you have to leave your closed mind and tendency to find fault at home if you really want to enjoy yourself - though most places put considerable effort into cooking something creative and novel.

So that leaves just one problem with the trend: its secrecy. It's all very well hearing about an underground trend, but if you can't find any access to the underground, then what's the point? Thankfully, a simple Google search with the name of a city should throw up something. The most complete global list of secret restaurants is found on the Salt Shaker blog at www.saltshaker.net/underground-dining-scene.

The links on this list don't always give direct contact details (that's the point, isn't it?), but they do give you useful pointers that make the hunt a whole lot easier. The secret restaurant movement is great fun, but right now it's trying hard to strike a balance between its new popularity and its underground roots, which is making many places shy of more publicity. In other words, if you go to one, please don't say I sent you.