For salsa:

Combine all ingredients without mashing avocado.

For Tacos:

In a small bowl, combine cumin, cayenne, salt, pepper, and coriander. Rub spice mixture generously on both sides of the tuna.

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.

Dice tuna into 1/4-inch cubes.

Spoon tuna over salsa into tortillas and squeeze a spritz of lime juice overtop.

Serve immediately.