All aboard the Orient express

THE JAPANESE CANTEEN 394 St John Street, London EC1 Tel: 0171-833 3222. Open seven days a week. Lunch 12 noon-2.30pm. Dinner 6-10.30pm Average price per person: £5 (without drinks). No credit cards

MAKING jokes about Japanese food involving bits of whale's blubber or raw tropical fish would, in fashionable grunge circles, be almost as bad as sporting a deerstalker or saying that Nelson Mandela should be put back in prison. Over the last couple of years, perceptions of this exotic cuisine have shifted from expensive, inscrutable, slithery or repulsive, to the very height of deliciousness and street cred.

The notion of cheap, fast Japanese food served in trendy surroundings where you queue for ages instead of booking, and it's really, like, great, was pioneered by the hugely successful Wagamama, near the British Museum, in London. A newer, cheap and speedy outlet, Moshi Moshi Sushi, is causing queues weekday lunchtimes above Platform One on Liverpool Street Station; while the Japanese Canteen, opened just two months ago in Islington, is already mega-popular.

It is probably OK to say that while completely, like, brilliant, right, Japanese food can sometimes be a little on the less-than-filling side. It seemed a wise precaution therefore to investigate both the new restaurants on one evening, beginning with Moshi Moshi Sushi - as a sort of pre-meal meal - and moving on to the Japanese Canteen.

Moshi Moshi is based on one of those ideas which is so simple and inspired that you cannot imagine that it will not instantly catch on: the food is served on a conveyor belt. The restaurant itself is in a sort of glass cage set on a balcony high above the station platforms. Diners sit on tall stools at a U-shaped bar, along which passes a line of little plates of sushi. People help themselves to a plateful whenever they fancy, stacking the empty plates in front of them for billing purposes. What with the trains coming and going below, buses stopping and starting in the street outside and the conveyor belt tootling along, it is rather like being in a toyshop where all the electrical items have come to life and gone mad.

There is far too much to do, though, to look out of the windows. First the plates must be matched to the price list: orange plates, 90p; green plates, £1.20; blue patterned plates, £1.50; blue plates with a net pattern, as the list says, challenging your observational powers, at £1.80. Next the sushi must be matched to the pictures on the menu card. Sushi consists of dainty chunks of cold, sticky rice with bits of raw fish on top, or rolls of rice with fish in the middle, and seaweed wrapped round. Morsels of every imaginable sea creature trundle cheerily by, from reassuring prawns, to octopus, sea urchin, and gizzard shad. On the bar between you and the travelling fish are chopsticks, jars full of pickled ginger, soy sauce and little dishes of green horseradish sauce, with instruction cards showing you how to put everything together.

There is a reversal of the traditional sex roles: with gentle males in pretty kimonos humbly preparing sushi in the middle of the conveyor, and fierce women in suits striding round on the outside taking orders for liquids. My girlfriend made the mistake of asking the sushi man for soup and a drink, whereupon one of the suited ladies bore down on the poor man hissing "I take the orders for soup."

He looked so hurt, we took against the cruel lady's soup before it even arrived. But it was rather good, almost clear, with a rich peanutty sediment and all manner of things lurking in there. At one point I had a big green seaweed beard stuck to my chin. My friend, still feeling resentful, kept pulling things out and saying "What's this? A bit of dog's colon?"

She wasn't wild about the sushi, or slime- balls as she called them, either. But although I would have to describe myself as a sushi fan rather than connoisseur, the selection struck me as particularly fresh and tasty. This impression would seem to be confirmed by the stacks of plates - nine or even 10 high - in front of the Japanese people dining there. Apparently sushi is just like sandwiches in Japan, which must make things rather expensive if you have to eat 10 sandwiches to fill you up.

We managed 10 platefuls between us, but by the time we reached the Japanese Canteen were very glad that we didn't have to wait in a queue. Funnily enough, one word which doesn't spring to mind in the Japanese Canteen is "Japanese". Built in a converted pub, with big windows, high ceilings and U2 blaring out, it is painted stark white, with bright lights and an open plan kitchen. There are plain blond wood tables and benches where reefer jackets and big jumpers rub shoulders with straight-from-work city suits. There seemed not to be any Japanese people there at all, though my companion did point out that one of the cooks had a black moustache.

The menu, however, offers exclusively Japanese fare - sushi, yakitori (grilled meat or veg on skewers), tempura (deep-fried fish or veg in light batter) and noodle soups. Best value (apart from bottles of champagne for £15 ) are the "Bento Boxes", complete meals for under a fiver. These are like smart TV dinners, with compartments containing vegetables, rice, salad, and a choice of main dish, such as salmon teriyaki, griddled chicken with ginger, or tempura, plus a bowl of soup.

It's not the most delicate or focused food you're ever going to eat but that isn't the point. The place can't miss. It's just the thing for a cheap, quick and jolly meal, performing roughly the same function as Pizza Express, only much more stylish and up-to-the-minute. We did feel, though, that we would have swapped a bit of stylishness for calories.

Thankfully, a few doors up we happened upon the Crowbar Caf where we fell upon frothy cappuccinos, muffins and custard pies. Even then we were unsated. It was very odd - almost as if all the little fish inside us were tucking into the muffins.

"What do you think the Japanese have for breakfast?" my friend asked, hungrily, as we finally headed for home.