Peel, seed and slice mango. Whirl in food processor or blender until smooth. Press through sieve to remove fibers. Measure 1- half cups. Combine gelatin and sugar in small saucepan. Add water. Cook and stir until sugar and gelatin are dissolved. Add lime juice and mango puree. Refrigerate until consistency of unbeaten egg white, about 1 hour. Beat egg whites until peaks form. Fold in mango mix. Whip cream. Add vanilla and fold into mango mix. Turn into pie shell. Refrigerate until firm, about 2-3 hours. To serve, top with whipped cream and sliced mango. Garnish with fresh mint.