Heat grill up to 600 - 700 degrees.
Lightly drizzle the Tuna with teriyaki sauce and season top, bottom, and sides of the tuna with Q-Nami Rub. Let sit while the grill is coming up to temp.
On the grill spray the bottom of a cast-iron skillet with cooking oil (avocado spray or duck fat) and sit on the grill upside down. Let cast iron come up to temp.
Place the tuna on the cast iron and let sear for 1 to 2 minutes. Flip and sear the other side for 1 to 2 minutes. We pulled our tuna steak when the internal temperature reached 100 degrees. We like it super rare. You can continue cooking to your preferred doneness.
Let rest for 5 to 10 minutes, slice across the grain, and finish with Lane's Original Smoked Salt.