SIS (simple is smart) recipe for a dry rub for Blackened Tuna Steaks.
To make a quick and straightforward rub. Mix together a tablespoon each of paprika and Old Bay seasoning, plus 1/2 tsp each of ground ginger, oregano, and mustard, and lastly, 1/4 tsp of cayenne pepper. This amount of cayenne pepper makes the fish fairly spicy; decrease the cayenne if you like a mild, non-spicy piece of fish. Generously coat the fish with the rub and let it rest for several minutes while you heat a grill pan or skillet.