Combine 1 1/2 cups sugar, cornstarch, and salt in a medium saucepan. Gradually add water, stirring until well blended. Cook over medium heat, stirring constantly, until thickened.
Beat egg yolks until thick and lemon colored; gradually add one-fourth of hot mixture to yolks. Stir yolk mixture into remaining hot mixture. Cook over low heat 2 minutes.
Remove from heat. Add butter, lemon rind, and juice, stirring until butter melts. Pour filling into pastry shell.
Beat egg whites (at room temperature) and cream of tartar until foamy. Gradually add 1/4 cup plus 2 tablespoons sugar. Beat until stiff peaks form. Spread over warm filling, sealing to edge of pastry. Bake at 350° for 12 to 15 minutes or until meringue is golden brown. Cool to room temperature.