Place the ahi tune in between paper towels and blot dry
Combine the sesame seeds, sugar, and spices together
Coat both sides of tuna with tamari
Sprinkle sesame mixture over both sides of tuna and slightly press into the flesh.
Heat a cast-iron skillet until a drop of water will sizzle. Add the oil and heat until very hot. With tongs, add the tuna to the pan and sear for 60 - 90 seconds or until golden brown. Flip using a metal spatula. (you may need to use a spatter lid)
Remove to a serving platter. Slice if using a single block of tuna.