Le Relais de Venise 120 Marylebone Lane, London W1

There's a lovely little fish and chip restaurant on Marylebone Lane called The Golden Hind, which is where I head when I'm in town and hungry. It's a bustling little place, always full, always good. But this review is not of The Golden Hind. Because many is the time Mr M and I have sat with our haddock and chips, wondering about the queue snaking around the street from the restaurant across the road.

The exterior of the French brasserie Le Relais de Venise has always looked bog-standard. The inside has dull-maroon banquettes and a ghastly explosion of peach flowers at its centre. And why would anyone queue in the dark and damp for bistro food? There must be at least a dozen places serving it within a mile.

Ignoramuses that we are, we'd forgotten the flurry of interest Le Relais de Venise caused when it opened five years ago due to its USP: it serves only one menu – there is no choice. Now, in an age when restaurants open and close faster than an inquiry into expenses at the Lords, why would such a one-trick pony of a place still be commanding queues five years on? It must be extraordinarily good, we'd say. We should go one day. Then we'd turn back to our supper and forget all about it.

Until last week, when the urge for food after a West End drinks party sent us to Marylebone Lane, ostensibly in search of battered fish. But then we noticed the queue opposite was shorter than usual, just four souls huddled in the doorway of Le Relais, dodging the empty beer bottles on the ground (left by earlier, long-haul queuers, presumably). Seems like a good time to try it out – after all, the one in Paris has been going since 1959 and still has lines outside.

There is, as I mentioned, no choice (and it's £19 whether you eat it all or not). As soon as we sit down, a waitress – dashing between tables, dispensing food and taking drinks orders at quite a lick – explains the concept, wearily. Well, you would too, after five years of the same line. "It's salad, steak and chips. How do you want your steak?"

That means rare, medium or well done – they hold no truck with fancy demands like, say, medium-rare. Ten seconds later our starter arrives – a reasonably perky green salad with walnuts and vinaigrette. One couldn't call it generous, but it does the job. I'm distracted by the matron-like head waitress, who oversees the serving of dishes and clearing of tables gimlet-eyed with a vast bunch of keys attached to her belt. No wonder the younger ones keep up a sprint.

The salad plates are whisked away and we barely have time to sip the Château de Nardon Bordeaux 2002 (£22) before the main course arrives. Again, measly sized plates but the thinly sliced entrecôte steak and French fries are piled high. Other reviewers have grumbled about the provenance (or lack thereof) of the steak and the thinness of the "famous sauce" covering it, but standards must have improved since it was slated back in 2005. The steak (the beef is now supplied by the reliable Donald Russell operation) is tender and well-flavoured, and the chips crisp and thin. The buttery, salty sauce is a tad heavy on the herbs (basil seems to be prevalent) but it is piquant and seems authentic.

We're just mopping up the last of the sauce with some baguette when our waitress hoves into view at top speed, bearing a tray with more steak, then more chips. "Seconds!" cries Mr M with pleasure. Whether this is munificence on the part of Le Relais, or actually just the other half of what would have been a normal restaurant portion cunningly disguised as such, it's actually quite a clever idea. It makes us feel as if we're at a friend's dinner party rather than a restaurant. The cooking is that kind of standard, too: skilled amateur rather than dazzling professional.

You won't get 18 choices of pudding at a mate's place, but that – bizarrely, given the concept – is what this place offers. We have a crème brûlée and praline liégeois (each £4.50) which are rather good. Mr M also has a plate of French cheeses (£6.50) which is yes, small, but each of the four is à point. A brisk espresso rounds things off and nudges the bill over £80. On the way home, we do the maths. The folk behind this mini-chain (two in London, plus Paris, New York, Barcelona and Bahrain) are making a mint.

So, not cheap, not outstanding, but I rather like Le Relais. The secret is to avoid the anticipation that comes with a lengthy wait. Come either early or late, and imagine you're in Paris – brusque, bustling Paris.

13/20

SCORES: 1-9 STAY HOME AND COOK, 10-11 NEEDS HELP, 12 OK, 13 PLEASANT ENOUGH, 14 GOOD, 15 VERY GOOD, 16 CAPABLE OF GREATNESS, 17 SPECIAL, CAN’T WAIT TO GO BACK, 18 HIGHLY HONOURABLE, 19 UNIQUE AND MEMORABLE, 20 AS GOOD AS IT GETS

Le Relais de Venise 120 Marylebone Lane, London W1, tel: 020 7486 0878 Lunch and dinner daily. £70 for two, including wine

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Reviews extracted from 'Harden's London and UK Restaurant Guides 2010'. www.hardens.com