In a small saucepan, combine water, 2 tablespoons sugar, and cornstarch. Cook over low heat until clear, stirring constantly. Remove from heat.
In a large glass or metal bowl, beat egg whites, cream of tartar, and salt until mixture is foamy. Mix in vanilla, then gradually add the 6 tablespoons sugar, beating constantly until meringue forms soft peaks. Gradually pour in cornstarch mixture, beating until stiff. Spread over top of pie and seal to the crust. Brown in oven if desired.