Divide red onion, avocado, corn, and 1/2 cup salsa among tortillas. Spread 2 tablespoons tuna on each tortilla. Garnish with avocado and cilantro as desired Yellowfin Tuna or Ahi Tuna is usually served either Raw, as in sushi or Seared. Directions: Place tortilla shells on plate. or Grilled. When I first had this tuna … Garnish with cilantro, if desired. Ahi Tuna (Yellowfin) Steaks Grilled with a Mediterranean Flair. Top with lettuce and tomato and cheese as desired. Grilled Mediterranean Ahi Tuna. Distribute tuna over the shell.