Season tuna steak with salt and pepper. Saute tuna steak over medium heat for two minutes on each side, and then remove from heat. Place lettuce on base of Sandwich Thins® roll, followed by the tuna steak, sliced onions, mango salsa, and the top of the Sandwich Thins® roll. *If store-bought salsa is not available, the ingredients to prepare yourself are: a mango, a pineapple, a jalapeno pepper, a pinch of cilantro, a red or green bell pepper, and a squeeze of lemon juice and lime juice. Chop the fruit and vegetables into small pieces and mix well. Dice the cilantro for garnish and add lemon or lime juice to taste.