Viajante, Patriot Square, London E2

Fifteen years ago, the Independent on Sunday hired Helen Fielding as a restaurant reviewer, and I lucked into the role of regular reviewer's companion. Our first outing was to a hilariously pretentious restaurant in Bayswater's Hempel Hotel, where we were served designer Thai food by a team of off-duty supermodels in an atmosphere of utter solemnity. It was ridiculous, but enjoyable, in a mad sort of way.

I-Thai ushered in a new wave of super-stylish hotel restaurants – Nobu, Asia de Cuba, Spoon @ The Sanderson – which served serious food to the kind of fashionable people who would really prefer not to eat anything. Some of those restaurants survive, but I-Thai is long gone. Helen Fielding, meanwhile, has fallen on hard times, forced into exile in the Hollywood Hills, where she somehow manages to scrape together the means to pay for her own meals.

When she returned to Britain recently, we reprised our old reviewing double act, with roles reversed. In the decade since Helen left London, the social centre of gravity has shifted east, from Bridget Jones's old stomping ground of Notting Hill, to Shoreditch and beyond. As an introduction to the current East End scene, Viajante seemed perfect, offering a cutting-edge gastronomic experience in Bethnal Green, the new frontier of urban edginess.

Artistic types may have settled its warehouses, but it's fair to say that Bethnal Green isn't yet famed for its restaurant culture. The converted Edwardian town hall which holds Viajante (part of a new designer hotel) stands in an unlovely landscape of pound shops and Sixties social housing. "It's the new Shoreditch," I assured a doubtful Helen – not much of a consolation, since she had never been to the old Shoreditch.

Viajante's gloomy bar area manages to be both spartan and over-designed. Despite a glamorous raised bar and sculptural light installation, the room has a stolid, municipal feel. The dining area is more attractive; two interconnecting rooms whose faux-casual mix of mid-century-modern furniture and contemporary design elements feels as of the moment as I-Thai's minimalism did in the mid-1990s.

Dominating the room is another contemporary cliché – the open kitchen. And boy, is this one open; Viajante is not so much a restaurant with an open kitchen, as a kitchen with an open restaurant. Seated a few feet from the pass, we had a ringside view of the spookily silent team of chefs, busily tweezering items on to plates from Tupperware boxes. "I don't want to eat food that involves tweezers," Helen whispered, inhibited by the proximity and intense gaze of head chef Nuno Mendes.

A graduate of El Bulli, Portuguese-born wunderkind Mendes gained mythic status as the Heston of Hoxton, thanks to his experiments at Shoreditch's Bacchus. More recently he has run a private supper club from his Dalston flat, where guests pay £100 a head for a mystery menu.

Mendes has imported that sense of adventure to Viajante. There's no menu; guests simply specify whether they would like six, nine or 12 courses, though this concept wasn't clearly explained to us. Instead, after a confusing hiatus, our waiter approached with the peculiar opening gambit, "Do you have any dietary requirements?" Well yes, some food would be nice. Nor were we shown a wine list. "They're a little controlling," decided Helen. "They'd never do this in LA. Everyone would have an allergy, or an intolerance, or be on a special diet."

What followed was a curate's egg of a meal; in fact, a curate's egg was pretty much the only thing we didn't eat, in the wave after wave of tiny, exquisite dishes that flowed our way. Some of these were superb: an intricate "spring garden"' salad in which every lovingly treated ingredient shone. Others seemed almost perverse, showcasing ingredients – chicken skin, raw squid, celery heart – which even a mother would find it hard to love.

Take that squid dish, dressed with samphire and slices of pickled radish, and served with dill oil and a granita of squid-ink which melted into an intense, black pool. It tasted wonderful, if you could ignore the claggy texture of the raw squid.

The hit-and-miss nature of this and other dishes left us feeling that experimentation had won out over common sense. How else to explain the actively nasty combination of jellied aubergine consommé with panna-cotta-like soy milk? Or the tapioca-like onion sauce, frogspawn-ish in texture, spooned over roasted celeriac? Or a chocolate bonbon, intensely flavoured with mushroom, which conjured up both sorts of truffle in one disorientating bite? As Helen said, "It's like a first date – he's trying too hard."

Mendes and his chefs join the waiting staff in bringing the dishes to the table. As each random set of ingredients was solemnly, and often incomprehensibly, listed – skate wing brioche with roasted yeast, bread with potato powder – we attempted to look serious, but started to lose it when we were told that "the next dish has an Alsatian theme".

This is a restaurant that clearly aims to be world-class, Mendes' passion isn't in doubt, and his ambition to establish Viajante as a beacon in an area which badly needs visitor attractions is admirable. But his mission is compromised by disjointed service and over-intellectualised food.

We ended with coffee, or rather Colombian full-wash coffee. That foodie trainspotterishness pretty much encapsulated the fussy joylessness of the Viajante experience, which ended up having more in common with I-Thai than we could have anticipated.

Viajante, Patriot Square, London E2 (020-7871 0461)

Food
Ambience
Service

£60/£75/£85 a head for 6/9/12 courses, before wine and service

Tipping policy: "Service charge is 12.5 per cent discretionary, of which 100 per cent goes to the staff; all tips go to the staff"