Orange Meringue Pie

1 baked 8 inch pastry pie shell
3 1/2 tablespoons cornstarch
3/4 cup white sugar
1 pinch salt
1 1/4 cups boiling water
2 tablespoons butter or margarine
2 slightly beaten egg yolks
6 tablespoons thawed, undiluted, frozen orange juice
4 teaspoons grated orange rind
2 egg whites
1/2 teaspoon vanilla extract
1/4 teaspoon cream of tartar
4 tablespoons white sugar
                   
1. Blend cornstarch, 3/4 cup sugar, and salt in a saucepan.
   Gradually stir in the hot water. Cook over medium heat,
   stirring constantly until thickened. Reduce heat to low.
   Cook and stir 5 minutes longer. Remove from heat. 
2. Mix butter or margarine, egg yolks, orange juice, and
   orange rind into the cornstarch mixture. Cook one
   minute more. Cover entire surface with clear plastic. Let
   cool just slightly, and pour into the cooled pastry shell.
   Cool to room temperature. 
3. In a clean glass bowl, beat the egg whites with vanilla
   extract and cream of tartar until foamy. Beat in 4
   tablespoons sugar gradually, and continue beating until
   meringue forms stiff and glossy peaks. Spread meringue
   in swirls over the filling; be sure to seal to the edge of
   the pastry. 
4. Bake at 375 degrees F for 10 to 15 mins, or till the meringue
   is tipped golden brown. Cool to room temperature.