1.Prepare a pre-meringue by mixing gelatin, cornstarch, and cold water in small saucepan. Stir until lumps are dissolved. Add boiling water. Bring mixture to boil and cook 1 minute, stirring constantly. Remove from heat and stir in sugar. Pour mixture into small bowl and refrigerate exactly 25 minutes. 2.After 25 minutes are up, beat egg whites and cream of tartar in medium bowl until soft peaks form. Add pre-meringue mixture and vanilla and contiue beating until mixture is very stiff and resembles whipped cream. 3.Fill 9-1/2 inch baked pie crust with your favorite pie filling and top with meringue mixture, being sure to seal in filling by touching meringue to all edges of crust. 4.Bake at 350 degrees until meringue is lightly browned, 15 to 20 minutes. Place in refrigerator, uncovered, until cool, then cover. (Another 9-1/2 inch pie plate makes a convenient cover.)