In a small bowl, sprinkle the gelatin over the cold water. Let stand for 5 to 10 minutes until softened.

In a mixing bowl, beat the egg yolks until light in color. Add 1/2 cup sugar, orange juice concentrate, lemon juice, orange zest and salt. Transfer mixture to saucepan. Cook over medium-low heat, stirring constantly, until the mixture thickens enough to coat the back of a spoon.

Remove from heat. Stir in the softened gelatin until completely dissolved. Allow the mixture to cool until it begins to thicken slightly but is not set.

In a clean mixing bowl, beat the egg whites until soft peaks form. Gradually add the remaining ½ cup sugar, beating until stiff glossy peaks form.

Gently fold the meringue into the cooled citrus mixture until no white streaks remain. Be careful not to deflate the mixture.

Pour filling into the prepared pie crust. Refrigerate for at least 4 hours, or until fully set.

In a chilled mixing bowl, beat the heavy cream until it begins to thicken. Add the powdered sugar and vanilla. Continue beating until soft to medium peaks form. Spread evenly over the chilled pie before serving.