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I saw this on the food network the other day and had to try it. It is very good, and not that difficult to make. 
1 teaspoon ground cumin
1/4 teaspoon cayenne pepper
1/2 teaspoon salt
1/2 tablespoon freshly ground black pepper
1/2 teaspoon ground coriander
12 ounces ahi (or albacore) tuna, cut into 1-inch-thick steaks
1/2 tablespoon olive oil
8 taco shells (available in most grocery stores)
2 limes, halved
Avocado Salsa, recipe follows
In a small bowl, combine cumin, cayenne, salt, pepper, and coriander. Rub spice mixture generously on both sides of the tuna.
Preheat oven to 350 degrees F for the taco shells.
Heat a nonstick pan on the stove over high heat. When pan is smoking hot, add olive oil, wait 10 seconds, then add tuna. Sear for 1 minute per side, or until fish is cooked on the outside, but rare on the inside. Transfer to a plate.
Separate taco shells and place them in the oven for 4 minutes (timing is everything here, since they go from perfectly done to burned after about 1 additional minute).
While the shells are heating, dice tuna into 1/4-inch cubes. To serve, fill all 8 taco shells halfway with salsa. Spoon tuna over salsa and squeeze a spritz of lime juice overtop. Serve immediately.
Avocado Salsa:
2 ripe avocados (ripe means it indents with the firm press of a finger), pit and skin discarded, diced into 1/4-nch cubes
2 medium tomatoes, diced into 1/4-inch cubes
1 cup lightly packed fresh cilantro leaves, coarsely chopped, stems discarded before measuring
1/4 cup diced red onion
3 tablespoons freshly squeezed lemon juice
1/8 teaspoon salt
1/4 teaspoon freshly ground black pepper
Add all ingredients to a medium-size bowl. Toss gently. DO NOT MASH AVOCADO
1 teaspoon ground cumin
1/4 teaspoon cayenne pepper
1/2 teaspoon salt
1/2 tablespoon freshly ground black pepper
1/2 teaspoon ground coriander
12 ounces ahi (or albacore) tuna, cut into 1-inch-thick steaks
1/2 tablespoon olive oil
8 taco shells (available in most grocery stores)
2 limes, halved
Avocado Salsa, recipe follows
In a small bowl, combine cumin, cayenne, salt, pepper, and coriander. Rub spice mixture generously on both sides of the tuna.
Preheat oven to 350 degrees F for the taco shells.
Heat a nonstick pan on the stove over high heat. When pan is smoking hot, add olive oil, wait 10 seconds, then add tuna. Sear for 1 minute per side, or until fish is cooked on the outside, but rare on the inside. Transfer to a plate.
Separate taco shells and place them in the oven for 4 minutes (timing is everything here, since they go from perfectly done to burned after about 1 additional minute).
While the shells are heating, dice tuna into 1/4-inch cubes. To serve, fill all 8 taco shells halfway with salsa. Spoon tuna over salsa and squeeze a spritz of lime juice overtop. Serve immediately.
Avocado Salsa:
2 ripe avocados (ripe means it indents with the firm press of a finger), pit and skin discarded, diced into 1/4-nch cubes
2 medium tomatoes, diced into 1/4-inch cubes
1 cup lightly packed fresh cilantro leaves, coarsely chopped, stems discarded before measuring
1/4 cup diced red onion
3 tablespoons freshly squeezed lemon juice
1/8 teaspoon salt
1/4 teaspoon freshly ground black pepper
Add all ingredients to a medium-size bowl. Toss gently. DO NOT MASH AVOCADO
