TOPPING: Whisk sour cream, lime juice and sugar in small bowl to blend. Spread evenly over cheesecake. Return cheesecake to hot oven. Let stand 45 minutes or less (Cheesecake will look very soft, but will set up when chilled.) Refrigerate cake until well chilled, up to 1 day. Run knife around pan sides. Remove pan sides. Place cake on platter. Arrange lime half-slices and peel around top edge of cheesecake.