'A beautiful taste of north Thailand in the centre of London's West End': TOM PARKER BOWLES reviews Khao- Sōi-I

If you're going to do one thing, do it well - and this new West End Thai does it dazzlingly There’s much to be said for restaurants that specialise in just one dish. Not least because they usually do it very well indeed. Tempura in Tokyo, say, where deep frying is taken to high art, each prawn coated in a diaphanous slip of lacy batter. Or Mexico City’s tacos el pastor from some hole-in-the-wall hotspot, the pork sliced fresh off the spit, crammed into a maize tortilla and slathered with homemade salsa. There are seething Sichuan hotpots, furious with chillies and peppercorns; and Peruvian cevicherias serving indecently fresh fish ‘cooked’ in lime juice.