Set a 10-inch saute pan over medium heat and add the olive oil. Once the oil is hot, season the tuna steaks on both sides with the salt and white pepper. Place the seasoned tuna in the saute pan and cook, undisturbed for 5 minutes. Turn the fish over and cook for another 5 minutes. The fish should be just cooked through. Remove the tuna from the pan and allow to rest for 3 to 4 minutes. Flake the tuna steaks into small pieces, place in a medium bowl and add the remaining ingredients.
Use a spatula or large spoon to toss the ingredients until well blended. Serve in lettuce cups, or with your favorite sliced bread for sandwiches.