01 - Set oven temperature to 350°F.
02 - Combine graham cracker crumbs, sugar, salt, and melted butter in a bowl. Press mixture evenly into the 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 add water while whisking. Cook over medium heat, stirring continuously until thickened and boiling. Boil for one minute, stirring.
04 - Lightly beat egg yolks in a separate bowl. Slowly whisk in 1/2 cup of the hot lemon mixture to temper. Return tempered yolks to saucepan, whisking constantly. Cook for 2 minutes, then remove from heat. Stir in lemon juice, lemon zest, and butter until smooth.
05 - Pour lemon filling into the cooled crust and set aside.
06 - Using a clean bowl, beat egg whites with cream of tartar until soft peaks form. Gradually add sugar while beating until stiff, glossy peaks develop. Beat in vanilla extract.
07 - Spread meringue evenly over the hot lemon filling, sealing the edges to the crust. Create decorative peaks using 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 at least 1 hour before serving.