At Bacchus in Hoxton, my friend and I quickly metamorphosed into the twin gods of whine. He kicked it off with a moan about the degree in access technology required to open the front door, and I hit back with a middle-aged complaint about the funky young waitress greeting us with a cheery, "Hello, my friends." He then mentioned the pretension that was a table laid with spoon and side plate but no knife or fork. In a tough, no-nonsense counterstrike, I cited the music - indie rock alternating with blues and ballads, as if some mischievous spirit was operating an invisible jukebox.

Then the menus arrived, and all previous irritants melted into irrelevance as we noted among the starters "baby squid, potatoes, garlic, chervil, black paella paint" and, littered throughout the mains, such area-of-urban-deprivation classics as "sesame crusted squab, cured foie gras, berries, milk skin".

Before we proceed, let me state that I wish Bacchus and its chef, Nuno Mendes, only well. The idea of transforming a nice old Victorian pub in a resolutely poor part of Hackney into a temple of molecular gastronomy is so eccentric, it warms the heart. But then so does the story of the Charge of the Light Brigade.

Mendes worked at El Bulli in Spain, where Ferran Adrià is Heston Blumenthal's great rival to be regarded as the world's leading chef of the kind, and what drew him from the Catalan coast to Hackney is one of many mysteries. Another is what a place offering "artichoke and honey-wine soup, pine nut ravioli, eringe, yogurt", and at a tenner a pop, imagines it's doing in a street market that could be used as an Only Fools And Horses location.

By the time an amuse-bouche of Greek yogurt foam with various bits and bobs had been announced with, "Guys, a present from Nuno, if you will", we'd both plumped for the six-course tasting menu that began with "sardine, rhubarb puree, citrus, rosemary-sake spray", the latter released from an atomiser. Three mouthfuls later, we were considering what possible point to all the effort there can have been.

The suspicion that Bacchus is far more an existential experience than a culinary one was undermined by the next two dishes. Sumptuously fatty pork jowl with a juicy, sweet langoustine and leek purée (everything here comes with offputting sludge) was good. Then came the triumph that suggested Mendes has real talent: "free-range egg, cooked at sixty-five degrees, dashi, chicken skin". I doubt you'd expect a battery egg at these prices, and the waitress wasn't helpful when, citing a fatal allergy to 65-degree-cooked eggs, I asked to go off menu with one done at 67.4. Even so, the medley was spectacular, the egg resting on shreds of chicken delicately flavoured with soy.

However, salmon belly with a date and hazelnut purée and much else was boring and uninspired. And as for "lamb shoulder, figs brulee, hijki paste, hot coffee", here we found the flavour-maximising, sous-vide method - whereby food is vacuum-packed and cooked incredibly slowly (in this case for 36 hours) - sadly exposed. The lukewarm lamb had such a bitter twang (you'd have thought hard about sending it back in a service station) that even the accompaniment of finely ground coffee beans couldn't rescue it. And how often do you find yourself compelled to say that?

Not for 30 years have I heard anyone say, "Oh my giddy aunt" without ironic intent. This was how my friend greeted a horrible pudding, "black olive financier, roasted pear ice cream, pine nuts", his first mouthful of ice cream revealing that, while it offered no hint of pear, it had been sprinkled with rock salt and drizzled with olive oil. For pity's sake.

We sat back over coffee, more disquieted than ever by the "fine dining in trainers" concept of making such labour-intense cooking "affordable" in an area so stubbornly resistant to gentrification. Never had the alternative concept of the all-day English breakfast - available in the greasy spoon opposite where the temperature at which the eggs are fried may not be a central issue - seemed half so alluring.

Rating: 5/10

Telephone 020-7613 0477
Address 177 Hoxton Street, London N1
Open Lunch Tue-Fri, noon-3pm, dinner Tue-Sat, 6pm-11pm
Price A la carte with wine, £50-£60 a head; six-course tasting menu, £40; nine-course Aventura menu, £55.