From America's Test Kitchen Season 6: Fish Steaks 101
Moist and rare in the middle with a seared crust, pan-seared tuna is a popular entrée in restaurants. This dish is so simple that we thought it would be easy to make at home, and set out to determine the best method.
Starting with high-quality tuna—sushi grade if possible—is paramount; we prefer the flavor of yellowfin. A thickness of at least an inch is necessary for the center of the tuna to be rare while the exterior browns. Before searing the tuna in a nonstick skillet, we rubbed the steaks with oil, then coated them with sesame seeds; the oil helped the seeds stick to the fish. The sesame seeds browned in the skillet and formed a beautiful, nutty-tasting crust. We learned that tuna, like beef, will continue to cook from residual heat when removed from the stove, so when the interior of the tuna was near the desired degree of doneness (about 110 degrees on an instant-read thermometer), we transferred it to a platter.
Serves 4 to 6
This recipe calls for a heavy ovenproof skillet. If you plan to serve the fish with the flavored butter below, prepare it before cooking the fish. Even well-dried fish can cause the hot oil in the pan to splatter. You can minimize splattering by laying the halibut steaks in the pan gently and putting the edge closest to you in the pan first so the far edge falls away from you.