This stunning nigiri sushi recipe by Hideki Hiwatashi uses hamachi, a highly prized fish that is also known as Japanese amberjack or yellowtail tuna. The chef uses a blowtorch to lightly char the fish and give it a wonderful smoky flavour and a delicate, flaky texture. Pair with other varieties of sushi, as seen in Hideki's mixed seared nigiri recipe, to scale this up into an impressive starter.