Blind bake the pie crust per the directions on the box or recipe. Once baked, chill the baked shell in the fridge on a wire rack while you prepare the filling and meringue.

Whisk the egg yolks until smooth in a medium-sized bowl, and set aside.

In a medium-sized saucepan, whisk together the sugar, flour, cornstarch, water, lemon juice, and lemon zest. Place over medium heat, stirring frequently, until it just comes to a boil. Take off the heat and stir in the butter.

Slowly stream about 1/2 cup of the sugar mixture into the bowl with the egg yolks while whisking fast and constantly. Once all of the sugar mixture is whisked in, slowly stream the egg mixture back into the pot while whisking constantly.

Place the pot back on the stove and continue to cook, frequently whisking until it comes to a boil. Boil for 1-2 minutes until thickened, then take off the heat.

Preheat the oven to 350°F.

Make the meringue by placing the egg whites and cream of tartar into the body of a stand mixer with the whisk attachment or in a large bowl with an electric hand mixer. Whip on medium speed until soft peaks form, about 1-2 minutes.

Add the sugar and salt and continue to whip on medium speed for another 1-2 minutes until glossy stiff peaks form; set aside.

Place the pot with the filling back on the stove and bring it to a boil while constantly whisking. This step will help secure the meringue to the filling.

Pour the filling into the pie crust. Top with the meringue and smooth it out so the meringue touches the crust on all edges, this will help prevent the meringue from weeping.

Place the pie in the oven on the bottom rack and bake for 20-25 minutes until the meringue is browned. If you think it is browning too fast, you can loosely cover it with foil, making sure not to touch the meringue.

Place the pie on a wire rack to cool for 1 hour and then place it in the fridge to set up for 4 hours.

Once cooled and set, slice and serve.