The prospect of a 20-course meal seldom fills me with much enthusiasm, but I’d heard that the Omakase Experiences at the Beaverbrook Town House in Chelsea, London, were not to be missed. In the interest of research, I dutifully made a reservation. My apprehension was compounded by the fact that I would have no advance knowledge of what I was going to eat. Omakase means “I leave it up to you,” and the chef creates a different menu each day, depending on which available fish are of the highest quality.