Combine the sesame seed in a small bowl.Coat each piece of fish in the seeds and set aside.
Heat the oil in a nonstick sauté pan over medium-High.
Add the fish to the pan and cook for 3 minutes on each side.
The tuna should still be pink inside. Transfer to a cutting board and cut into 1/4-inch slices.
Arrange the lettuce , tomatoes,cucumber,onion….
Combine all the ingredients and drizzle a little over the salade