Blackened tuna is a type of whole fish steak that is coated in Cajun seasonings and pan seared on a hot frying pan. This type of seasoning may be purchased from a specialty food store, or blended together by the chef, and is generally hot and spicy in nature. The coating of seasonings tends to react with the heat of the skillet in which this dish is prepared, creating a burnt and crusty exterior. The inside of the fish, due to the short time frame in which this process is completed, remains moist and flaky.
The term blackened is the name given to a specific technique for pan searing fish that was developed by a chef in Louisiana. The types of spices and seasonings used to coat the food are generally categorized as Cajun. Some gourmet specialty food stores sell bottles of blackened seasonings, though many cooks prefer to blend their own unique version. These seasonings may be used on any type of meat that will be prepared in a hot skillet or grilled. Blackened tuna, however, is traditionally cooked in a cast iron skillet.
The fish, when properly seared, will appear black, giving rise to its name. This is a result of the reaction between the spices and seasonings and the heat of the skillet. The exterior of the fish, when exposed to the extreme heat of the cooking pan, literally burns, forming a crispy crust around a hot and flaky interior. Cast iron tends to be able to sustain heat at a higher temperature than other types of metals used in cookware. The surface of the pan should be hot enough that it causes oil to smoke when drizzled into it.
The fish should be exposed to the heat no longer than two minutes on each side. If the skillet has been properly heated, the fish will burn on the outside without overly cooking on the inside during this length of time. To encourage the blackening process across the surface of the tuna, the cook may dredge the seasoned meat in butter before placing it into the skillet. The blackened tuna should be hard and crunchy on the outside, and moist and tender on the inside, when removed from the pan.
Any variety of tuna may be used, whether yellowtail, Pacific bluefin, or another type that better suits the chef and the availability of local fish markets. Blackened tuna tastes best when made with fresh, whole steak fish that has not undergone any freezing processes. Though frozen and thawed tuna can be used, the fish tends to lose a small amount of moisture and firmness of flesh that is maintained in a fresh steak. The fish should be rinsed and patted dry prior to use in the recipe to remove any excess negative fish flavors and prepare it to better bind with the seasonings.