Beat egg yolks until thick. Add 1/2 cup sugar, salt, and passion fruit juice. Cook over low heat until thick, stirring constantly. Add gelatin which has been dissolved in cold water. Add lemon rind and cool until slightly congealed. Beat egg whites with remaining 1/2 cup of sugar. Fold slightly beaten egg whites into cooled yolk mixture. Pour into cool pie shell. Chill until nice and stiff. Serve with whipped cream and enjoy.