Ahi Tuna Done Right
If you eat seared tuna exclusively when dining out because the thought of making it at home intimidates you, fear no more. Searing fish is a very simple process. Actually, the most important aspect is the quality of the fish. Start with the best and the fish does the rest. Ahi tuna, also known as yellow-fin, is moist, supple and best served when lightly seared on the outside, leaving the inside tender and downright raw in the middle. Because the fish should be raw, not rare, you must start with the very best, sushi-grade ahi. If you can't find high-quality ahi, save this recipe for another day. As for nutrients, tuna is widely known to be rich in protein and Omega-3 fatty acids, which help prevent inflammation, regulate blood pressure and protect against cardiovascular disease.
Regarding flavor, you'll adore this Asian-inspired marinade – a zesty blend of citrus-spiked ponzu sauce, soy sauce, sesame, lime, ginger and garlic. You can marinate the tuna in the mixture for up to 1 hour before searing (don't marinate any longer or the fish protein will actually "cook" in the acidic ingredients).
In a shallow dish, whisk together the ponzu sauce, soy sauce, sesame oil, lime juice, ginger, garlic and mustard. Season both sides of the tuna steaks with salt and pepper and add the tuna to the ponzu mixture. Turn to coat both sides (when marinating, cover the fish with plastic and refrigerate for up to 1 hour).
Heat the olive oil in a large skillet over medium-high heat. Add the tuna steaks to the hot pan and cook 30 to 45 seconds per side, until seared on the outside and raw in the middle.
Slice the tuna crosswise into 1/4-inch thick slices and arrange on a serving plate. Top with chopped green onions.