Colony Bar and Grill, 7-9 Paddington Street, London

It's a truism in marketing that you sell the sizzle, not the steak. The sizzle-sellers have been hard at work building a story for Colony, the latest venture from star chef Atul Kochhar, of Benares fame. According to the pre-publicity, Colony's tapas-style menu would be inspired by Indian street food, specifically "the marinades, aromatic flavours and grilling methods" of the street traders of colonial Asia. Sounds great, doesn't it? But hang on – street food and the Raj? Isn't that two different stories we've got going on there? Surely only the most educated palette would be able to differentiate between colonial and post-Independence street food?

Still, the spiced-up pre-opening sizzle was effective enough to get the juices flowing; particularly as Atul Kochhar's earlier excursions into Anglo-Asian cooking include the thrilling Vatika, set in a leafy Hampshire vineyard. Colony, in slightly less leafy Marylebone, calls itself a bar and grill, but the menu is far less casual than this implies. Rather than serving a selection of patties, puris and grilled meats, or going down the Anglo-Indian route pioneered by Chutney Mary, the restaurant offers complex, recondite dishes which would have the memsahibs calling for the smelling salts. Roasted mallard marinated in lindi peppers and stone moss? Lamb meat loaf infused with rose petals? Veal vindaloo with coriander chips? Whatever this is, it certainly isn't street food.

The restaurant, too, doesn't conform to expectations. Nothing about this converted All Bar One just off Marylebone High Street signals Indian restaurant. The name evokes the vanished glamour of Raffles hotel and the woosh of the punkawallah's fan. We find ourselves sitting in a beige, windowless cube which feels like the panic room they'd herd hotel guests into should the natives start revolting.

Judging by the swishness of the bar, that's where all the money has been spent. In the small, underlit restaurant area, exotic as a stock cube, the only decorative touches come from some hotel lobby artwork and, as a passing nod to the tropics, a single spotlit palm.

Only the cocktail list conforms to the colonial theme, with such offerings as Empress of India, based on cardamom-infused gin and champagne. We lounged colonially in the bar for some time, but the sun was setting on the empire when our drinks finally arrived, by which time we'd transferred to our table in the panic room.

Weirdly, given all the pre-match talk about street food and Indian tapas, there are no starters on the restaurant menu – just a number of main course dishes, served in tasting portions (though not, at £9-£15.50 a pop, at tasting prices). Following the example of our neighbour, another undercover food critic, we commandeered a bar menu and ordered a few small dishes from it in place of starters.

Things began rather prosaically with a complimentary pre-starter which was, to all intents and purposes, an onion bhaji, an oil-less but heavy mouthful of fried potato and onion, revved up with a slash of tamarind sauce. The bar snacks-turned-appetisers were more exciting; particularly a cube of char-grilled barramundi, fragrant with coriander, lime and chilli, and sautéed calamari which delivered a chilli kick.

Mains are designed to be shared (the suggestion is four to six between two people). Ours ranged from the relatively traditional – an aromatic rogan josh-style dish of slow-cooked shoulder of mutton – to a vivid and precisely cooked piece of monkfish, roasted in the tandoor, and served with crab vermicelli. Quite why the inventive Kochhar felt the need to include a version of chicken tikka masala on the menu is a mystery; we ordered it to see if they'd done anything interesting with it. They hadn't; the Colony version was authentically inauthentic, in its creamy sweetness and brick-red colour. Side dishes included terrific smoky aubergine, cooked in a sauce flavoured with stone moss, and light and buttery naan.

The fusion concept seems to have extended to the service, which manages to combine faffing and fluffing with rather patchy delivery, from a team comprising sultry female greeters, Indian waiters, a French manager, and the looming David Dickinsonian presence of genial co-owner Carlo Spetale, whose signature cocktail, it is probably fair to say, would not be the Shrinking Violet. No fewer than three members of staff urged us to try the mango dessert, a dense, super-sweet mango paste in a cigar-shaped tuille, which we liked better than our other choice, a clammy square of clove-spiced rice pudding.

With a £39 bottle of Albarino, our bill came to around £50 a head, before service. Even though many of the dishes we tried were very good, they weren't quite good enough to earn Colony a rave review. Perhaps misled by all that sizzle, I'd been hoping for a masala of a meal – mixed-up, spicy and full of zing. Instead, the spice that Colony brought to mind was vanilla; sweet and useful, but a bit ordinary.

Colony Bar and Grill, 7-9 Paddington Street, London W1 (020-7935 3353)

Food
Ambience
Service

£50 a head before service, including wine

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"