Bake the crust in a preheated oven (350 F) until the crust is golden brown. Now, combine cornstarch with sugar and water in a heavy-bottom saucepan over medium heat. Let this mixture bubble for a few minutes and reduce until it has a thick texture.

Now, whisk the egg yolks in a bowl by slowly adding three spoons of the thick filling and stir the egg mixture continuously. Add lemon juice, lemon zest, butter, and tempered eggs to the thick mixture in the saucepan and let them slightly bubble.

Pour the thick filling into the prebaked crust and set it aside to cool completely. Now, whisk a tablespoon of starch with sugar in a pan. Add a half cup of water and stir. Let the mixture bubble until it thickens. Now, set it aside to cool completely.

Beat the egg whites until soft peaks are formed and add sugar and vanilla to it. Add the cooled mixture (cornstarch-sugar mixture) to the egg whites while you continue to beat until stiff peaks are formed. Spread this meringue over the pie and tap top with a spoon to form small peaks.

Bake this pie in the preheated oven (350 F) until it’s brown in color and let it cool completely. Then refrigerate it by covering it with a cake carrier to keep the meringue undisturbed.