Grill Pineapple Slices, Uncovered, Over Medium Heat For 5-7 Minutes On Each Side. Chill For 30 Minutes. Dice The Pineapple; Place In A Bowl. Stir In The Onion, Jalapenos, Cilantro And Lime Juice. Refrigerate For 1 Hour Or Until Chilled. Brush Tuna Steaks With Oil; Sprinkle With Salt And Pepper. Grill, Covered, Over Medium Heat For 5 Minutes On Each Side Or Until Fish Flakes Easily With A Fork. Serve With Pineapple Salsa.