01 - Set oven temperature to 350°F.
02 - Combine graham cracker crumbs, sugar, salt, and melted butter in a medium bowl. Press mixture evenly into bottom and sides of a 9-inch pie dish. Bake for 8 to 10 minutes until lightly golden. Allow to cool completely.
03 - In a saucepan, whisk together sugar, cornstarch, and salt. Gradually whisk in water and cook over medium heat, stirring constantly, until thickened and boiling. Continue boiling and stirring for 1 minute.
04 - Lightly beat egg yolks in a bowl. Slowly whisk 1/2 cup of hot mixture into yolks to temper, then return yolk mixture to saucepan, whisking constantly. Cook for 2 minutes, then remove from heat. 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 form. Incorporate vanilla extract.
07 - Spread meringue evenly over hot lemon filling, sealing edges to crust to prevent shrinkage. Create peaks with the back of a spoon.
08 - Bake at 350°F for 15 to 18 minutes until meringue is golden. Cool at room temperature for 1 hour, then refrigerate for a minimum of 1 hour before serving.