38 Grosvenor Street, London, W1K 4QA, United Kingdom

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LSL Capital, the backers of Jamavar, Mimi Mei Fair and Bombay Bustle, launched Koyn in September 2022. Just off Grosvenor Square, Koyn is spread over two floors and serves Japanese food, with a robata grill being at the heart of the kitchen. The executive chef is New Zealander Rhys Cattermoul, who was previously executive chef of Nobu in Hong Kong, and prior to that spent eight years at Nobu Berkeley, with five of those years as head chef. Koyn is in a redevelopment of the former Canadian Embassy, and is smartly decorated, the tables well-spaced and with an open sushi counter. The restaurant can seat up to 240 people at one time, with sixteen chefs working tonight.

The wine list had 196 labels and ranged in price from £47 to £11,500, with a median price of £153 and an average markup to retail price of just 2.8 times, which is distinctly moderate by London standards, never mind for Mayfair, where 3.3 times or more is normal these days.  Sample references were Churton Sauvignon Blanc 2019 at £58 for a bottle that you can find in the high street for £25, Pichler Federspiel Riesling 2020 at £75 compared to its retail price of £19, and Boekenhoutskloof Cabernet Sauvignon 2019 at £99 for a wine that will set you back £42 in the high street. For those with the means there was Marchesi Antinori Tignanello 2019 at £310 compared to its retail price of £154, and Domaine Arnaud Ente Meursault 2009 at £995 for a wine whose current market value is £764. There was also a substantial selection of sake, including some with serious price tags. For example, the Tatenokawa 1 “Zenith” Yamadanishiki (was listed at £2,950, actually below its retail price at nearby Hedonism Wines. The highest grade of sake, dai-ginjo, has its rice polished to 50% or less of its original weight, but this ultra-expensive sake (using rice from Yamagata prefecture) has a ratio of just 1%, a process that takes 75 days. The ten regular dai-ginjo sakes on the list ranged from £101 to £245 in price, with seven further premium sakes including “Zenith”. 

An initial canape was lean tuna in little rice crackers, known as senbei.  The rice crackers were blended with nori, then dried and finally fried, filled with tuna tartare flavoured with a little wasabi. These were genuinely good. The rice crackers were delicate, the tuna had very good flavour and the spicing was nicely controlled (15/20). Also impressive was rock shrimp tempura served with a series of dips. This dish is quite common in upmarket Japanese style restaurants (Zuma, Roka etc), but here the batter was unusually delicate and the prawns precisely cooked through (easily 15/20). 

We then tried some sushi. The rice was warm, roughly at room temperature, which is fine. Many London restaurants mistakenly serve sushi rice straight out of the fridge, a cardinal sin in Japan. The shaping of the rice (the “shari”) could have been more precise but the toppings (“neta”) were of good quality. Scallop was sweet, akami tuna had quite silky texture and hamachi had good flavour. The only issue was that the sushi was served with pickled ginger (fine) and clearly fake wasabi i.e. coloured horseradish (not fine). When I mentioned this I was brought a wasabi root with freshly grated wasabi, which was lovely, but I shouldn’t have to play some sort of game with the kitchen in order to be served proper wasabi, especially at the price point of Koyn (14/20, with a mark deducted for the horseradish). Less impressive were unagi (river eel) rolls, the eel having decent enough flavour but not tasting like the lovely eel that I have been fortunate enough to eat in Japan (13/20).

Mixed vegetable tempura included carrot, mushroom, aubergine, enoki mushroom, squash and courgette. These were pleasant, again the batter being quite delicate, though the vegetables themselves having limited flavour (14/20). It is perhaps unfair to compare vegetables in the UK to the remarkable specimens served at high end restaurants in Japan, a country with arguably the best quality vegetables in the world. This was followed by spicy tuna on crisp rice base, which was unusual but worked nicely enough, the tuna again being of quite good quality, the spicing cutting through the richness well (14/20).

The restaurant has a robata grill, and we tried a few grilled items. A high-quality Orkney scallop had good natural sweetness, was carefully cooked and was coated with sesame, which worked well with the shellfish (15/20). An enormous tiger prawn had the flesh extracted from its shell, then pieces carefully put back for display. This was a huge prawn and it was cooked well (14/20). Sweetcorn on the cob was fine but more ordinary, served not quite as hot as ideal (13/20). “Chilean sea bass” is a fish that is really Patagonian toothfish, but is marketed as Chilean seabass for obvious reasons. It is actually a pretty good fish to eat, with a resemblance to sea bass in taste, and here was cooked nicely (14/20). I was impressed by grilled cabbage with koji dressing, a sweet yeasty dressing of fermented cooked grain. The cabbage was very accurately cooked and was robust enough to stand up to the quite strong flavour of the dressing (easily 14/20). I am always impressed when a kitchen can take a humble ingredient and make it special. It seems to me to take more skill to make a humble cabbage into something memorable than to simply cook a luxury ingredient like langoustine or turbot. Finally, I tried smoked lamb with black bean miso, mushroom and pickle, the meat being tender and its flavour working well with the miso (14/20).

Service was excellent, with our table being looked after by a particularly attentive and friendly waitress called Anca. Wine topping up was impeccable. The bill was £255 per person but I was being treated to this meal. If you ordered more carefully and shared some more modest wine then a typical cost per person might be around £150. Koyn is in the heart of Mayfair and is never going to be a cheap outing. However, the food was good, probably better than it really needs to be, and the service and setting were impressive. The restaurant was completely packed, both upstairs and downstairs, on a weekday evening in February and although the price point is high, Koyn clearly understands its clientele, and is pitched at a level that its customers feel happy paying.

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  • Charles Cohen

    "I shouldn’t have to play some sort of game with the kitchen in order to be served proper wasabi". Oof!