Heat oven to 450°F. Make pie crust as directed on box for One-Crust Baked Shell using 9-inch glass pie pan. Bake 9 to 11 minutes or until light golden brown. Cool completely, about 30 minutes.
Meanwhile, in 2-quart saucepan, mix 1 1/4 cups sugar, the cornstarch and salt. Gradually stir in cold water until smooth. Cook over medium heat, stirring constantly, until mixture boils. Boil 1 minute, stirring constantly. Remove from heat.
In small bowl, beat egg yolks with fork. Stir about 1/4 cup of hot mixture into egg yolks. Gradually stir yolk mixture into hot mixture. Cook over low heat, stirring constantly, until mixture boils. Boil 1 minute, stirring constantly.
Remove from heat. Stir in butter, lemon peel and lemon juice. Cool slightly, about 15 minutes. Pour into cooled baked shell.
Reduce oven temperature to 350°F. In small deep bowl with electric mixer, beat egg whites, cream of tartar and vanilla on medium speed about 1 minute or until soft peaks form. On high speed, gradually beat in sugar 1 tablespoon at a time until stiff glossy peaks form and sugar is dissolved. Spoon meringue onto hot filling; spread to edge of crust to seal well and prevent shrinkage.
Bake at 350°F 12 to 15 minutes or until meringue is light golden brown. Cool completely, about 1 hour. Refrigerate until filling is set, about 3 hours. Store in refrigerator.