1.Toss The Pineapple, Cilantro, Red Onion, And Lime Juice Together In A Bowl Until Evenly Mixed; Set Aside. 2.Rub The Mahi Mahi Fillets With The Sesame Oil To Lightly Coat. 3.Sprinkle The Sesame Seeds Evenly Over One Side Of Each Fillets; Gently Press The Seeds Into The Fish To Assure They Stick. 4.Heat The Vegetable Oil In A Large Non-Stick Skillet Over Medium Heat. 5.Lay The Fillets With The Seeded Side Down Into The Hot Oil; Cook For 4 Minutes, Turn, And Continue Cooking Until The Flesh Turns Opaque And Flakes Easily With A Fork, Another 3 To 5 Minutes. Serve With The Pineapple Mixture.