Searing Tuna for a Rare Centre

Searing tuna for a rare centre depends on one non-negotiable: the pan must be screaming hot. A heavy cast-iron or carbon-steel skillet held over high heat for three minutes - until a wisp of smoke rises from the dry surface - is the right tool. The tuna goes in completely dry, oiled and seasoned, and is left untouched: 45 to 60 seconds on the first face, 30 to 45 on each of the others. The aim is a thin band of golden-brown crust giving way to a vivid pink-red interior. A pan that's anything less than smoking will steam the surface and overcook the centre before any crust forms; stainless steel struggles to hold the necessary heat, which is why cast-iron or carbon-steel is the right choice. Rest no more than two minutes before slicing thinly across the grain, so the interior keeps its colour and the slices fan cleanly.