Betterment at the Biltmore, Mayfair

Given the significant budgets five star hotels in London have access to, the network of connections to the world's best chefs and operational staff, the beautiful (usually) and vast (sometimes) spaces they can dedicate to kitchens and dining halls, it's somewhat surprising how few hotel restaurants turn out to be any good. For every Alyn Williams at the Westbury*, where every course on a recent tasting menu was touched with pure genius, there's a Siren at the Goring, uneven and disorentating. For every Holborn Dining Room, where the staff are the best in town and the pies miniature works of art, there's the ever-changing restaurant at the Sanderson, who don't seem to be able to hang on to a head chef for more than a month, a rudderlessness reflected in their half-assed, dreary menu.

But even if you manage to snag a well-regarded head chef, a beautiful dining room and an association with one of the best hotels in town, success is by no means guaranteed. I may be in the minority (the numbers it does suggest I very much am) but I've never been particularly keen on Berners Tavern, because no room decked out like the Paris Salon is going to distract me from the fact I'm paying £22 for fish and chips with - horror of horrors - crushed garden peas instead of proper mushy. So it's fair to say I didn't have stratospheric expectations for Betterment, Jason Atherton's new project in the Biltmore on Grosvenor Square, which - at first glance - serves a faintly similar menu of international modern hotel favourites.

And yet. And yet. From the moment the house bread at Betterment (I really do not like that name) landed on the table, it was clear that this was going to be a step above the average hotel restaurant experience. Steaming hot, with a firm but yielding crust and served with room-temperature salted butter, this was an unimpeachable bread course, every detail of it correct. And it's that kind of attention to detail - exacting but enjoyable, if occasionally a bit leftfield - that carries through to everything the Betterment produce, to often quite wonderful effect.

For example, on paper, raw langoustine dusted with powdered, dried summer berries sounds like the kind of thing that could very easily sail very close to disgusting, but instead was a delight, the fruit powder serving as a kind of gentle seasoning that still allowed the sweet flesh of the seafood to shine. It was experimental, definitely, and ever-so-slightly wacky perhaps, but still a mature, well-crafted starter that impressed on every level.

Roast scallop came cutely framed by some sliced cep mushrooms, the advertised girolles forming part of a parmesan-seasoned mixture underneath. I didn't get to try any of this myself, as it had disappeared before I'd looked up from my langoustines, but I suppose that only goes to show how good it was.

99.9% of the time, the answer to the question "Should I use rose water in this starter?" is a resounding "Bloody hell no", and yet this neat arrangement of white crab meat, ajo blanco and a generous layer of caviar seemed to weather the intrusion of Eau de Old Lady quite well. It probably helped that there was so much caviar (nobody has ever complained about there being too much caviar), and that the crab was lovely and sweet and fresh. And it also probably helped that there was hardly any rose water in it at all. This is a good thing.

In contrast to the other relatively complex starters, king crab was prepared and presented quite simply, cut into bitesize portions and spritzed with yuzu and lime. The best seafood rarely needs much doing to it (take note Norma) and this crab, previously frozen but none the worse for it (king crab freezes very well), was a very fine bit of seafood indeed.

Mains continued the theme of being inventive, attractive, and charmingly eccentric. My own ox cheek tortellini had a good bite - firm but not chewy or hard, the perfect done-ness - a nice rich filling, and the horseradish velouté wasn't the least bit bitter but instead kind of earthy and salty and quite lovely. In lesser hands, this kind of geographic pick'n'mix cuisine, bits from Italy and Japan and France and the US, would be confusing and disappointing, and Lord knows enough hotel bistros are. But it's abundantly clear that not only does Atherton (or whoever) write a good menu but he has assembled an incredibly accomplished kitchen team - lead by Ben Mellor, at least on the night we visited - to make sure it all gleams with style and finesse.

And talking of accomplishments, blimey the chips. I said on the night on the meal on Instagram, belly full of negroni and a glass or two of Sauvignon Blanc, that they were the best chips I've ever eaten. Now, sober and less prone to hyperbole, I should probably revise that statement. They are, in fact, definitely the best chips I've ever eaten. Sorry Blacklock, sorry Chik'n'Sour, sorry Hawskmoor - the Bettermore's beef dripping chips were in every way perfect, silky smooth inside with a good crunch on the surface, seasoned sensitively and glowing with colour and flavour, I can't imagine anywhere else beating them, now or ever. True, they were £9 for about 8 of them but if that's the price of perfection, so be it.

A sharing portion of turbot was a glorious thing - meaty and firm in texture with a great taste and nice crisp skin. There would be a lot to be said for turning up at Betterment, ordering this and a few dozen portions of chips and calling it a lunch. I suppose that's the beauty of a menu as intelligently drawn up as this, the flexibility to enjoy your food in a myriad of different ways. Or maybe I'm just fantasising excuses to order a lot, lot more of those chips.

I didn't try the venison, but it looked the part and I didn't hear any complaints. I did get to try some of the onion flower with chive emulsion, presumably a tongue-in-cheek tribute to the Outback Steakhouse blooming onion, something that I would ordinarily chide as a bit naff if a) it hadn't been so tasty and b) we weren't all having such a great time.

There was one more dish of a cheesecake that for some reason I only photographed the non-cheesecake part of, which was clever of me, but trust me this again was wonderful. Initial disappointment at being served a 'deconstructed' cake soon turned to delight when it was sampled - a basque-style baked affair this was, incredibly rich and buttery and so fiercely authentic it could have come from the kitchens at La Viña in San Sebastián.

This wasn't an PR-led invite or anything like that but it was a birthday treat, and I didn't see the bill. You can probably work out how much the four of us spent by cross-referencing with the menu but I imagine it wouldn't have been much less than £100 a head, possibly a little more. That is not a cheap dinner, of course, although you can spend a lot more in the area - we all knew what we were letting ourselves in for booking into a five star hotel restaurant in Mayfair. What came as more of a surprise - and delight - was food this playful and full of personality and flavour, top ingredients treated well but without overdue reverence, the kind of thing you rarely see anywhere never minds in a restaurant that needs to keep so many different, and often competing, interests happy. For all my moans and groans about London food recently, there are, after all, still places that dare to be different. Cherish them wherever you find them, and make sure you get yourself down to the Betterment. Even if just for those chips.

9/10

*Alyn Williams at the Westbury is, at time of press, Alyn-less. I'm hoping they'll sort something out though because that place really is good.