01 - Set oven temperature to 350°F.
02 - In a medium bowl, combine graham cracker crumbs, sugar, salt, and melted butter. Press the mixture evenly into a 9-inch pie dish, covering the bottom and sides. Bake for 8 to 10 minutes until lightly golden, then allow to cool completely.
03 - In a saucepan, whisk together sugar, cornstarch, and salt. Gradually add water while whisking. Cook over medium heat, stirring constantly until the mixture thickens and reaches a boil. Continue to boil for one minute, stirring.
04 - Lightly beat the egg yolks in a separate bowl. Slowly whisk a half cup of the hot mixture into the yolks to temper them, then return yolks to the saucepan and continue whisking. Cook for an additional two minutes off the heat. Remove from heat and stir in lemon juice, lemon zest, and butter until smooth.
05 - Pour the lemon filling into the cooled crust and set aside.
06 - In a clean bowl, beat egg whites with cream of tartar until soft peaks form. Gradually add sugar while beating until stiff, glossy peaks develop. Incorporate vanilla extract.
07 - Spread meringue evenly over the warm lemon filling, sealing edges to the crust. Use the back of a spoon to create decorative peaks.
08 - Bake at 350°F for 15 to 18 minutes until the meringue turns golden.
09 - Allow the pie to cool at room temperature for one hour, then refrigerate for at least another hour before serving.