"Ahi" is a Hawaiian term that refers to yellowfin tuna and bigeye tuna, two distinct tuna species that taste the same and are prepared in the same way. Yellowfin tuna is the most common species, and the one you might order in a restaurant. While this species of tuna is commonly sold cooked and canned as "light tuna," ahi refers to sliced tuna steaks. Ahi is frequently pan-fried just enough to sear the outside of the tuna steak while the inside remains red or pink. The USDA food safety guidelines recommend cooking the ahi to an internal temperature of 145 degrees Fahrenheit.
Season or marinade the ahi tuna steaks. The most basic seasonings are simple salt and pepper, but you might try a seafood seasoning blend or a wet marinade with olive oil and lemon juice. If desired, coat the ahi with a mixture of panko breadcrumbs and spices.
Preheat a skillet over medium to medium-high heat with just enough oil to coat the bottom of the pan to prevent sticking. The oil is ready to fry the tuna when a drop of water in the center of the pan quickly sizzles and disappears.
Lay the ahi tuna in the pan, leaving a space between each tuna steak so you can easily turn them when needed. Fry the first side in the oil for about five minutes or until the exterior turns a rich golden brown.
Turn the ahi steaks over after the first side develops a golden brown color. Fry for another five minutes to develop the same color on the second side.
Check the internal temperature with a meat thermometer inserted in the thickest part of the tuna steak. If it has not yet reached 145 degrees Fahrenheit, flip the ahi back to the first side and continue frying until the safe temperature is reached. Turn the tuna every few minutes while cooking to prevent burning the exterior; reduce the heat if the exterior cooks much faster than the inside.