Prepare A Grill For High Heat. Season The Salmon Fillets With Salt And Pepper And Drizzle With Olive Oil. Whisk Together The Mayonnaise, Mustard, Olive Oil, Garlic, Lemon Juice, Tarragon, Salt And Pepper; Set Aside. Lightly Oil The Grill Grate. Cook The Salmon On The Grill Until The Fish Flakes Easily With A Fork, 5 To 10 Minutes. Place On A Serving Plate And Top With The Prepared Sauce.