Bake the crust

• Line a deep dish pie pan with the thawed pie crust and crimp the edges.
• Weigh the crust down with parchment paper and baking beads or sugar.
• Bake according to the package instructions.

Start the lemon filling

• Preheat the oven to 350°F (175°C).
• In a saucepan over medium heat, whisk the water, sugar, lemon zest, lemon juice, cornstarch, butter, vanilla and salt.
• Stir continuously until the butter is melted, the sugar has dissolved and the mixture is slightly thick.

Thicken with the egg yolks

• Reduce the heat to low and add the egg yolks to a mixing bowl.
• While stirring, slowly ladle in some of the lemon mixture.
• Stirring constantly, slowly stream this mixture back into the saucepan.
• Turn the heat back to medium and stir until smooth and slightly bubbly, the consistency of pudding.

Fill the crust

• Spread the lemon filling into the baked pie crust.
• Set aside and keep warm.

Make the meringue

• With a hand or stand mixer fitted with the whisk attachment on low, beat the cream of tartar and egg whites just until peaks start to form.
• Continue mixing while slowly adding the sugar and salt, then turn the mixer up to medium.
• Mix until stiff smooth peaks form and the mixture looks shiny.

Top and bake

• Spread the meringue over the warm pie filling.
• Use the back of a spoon to form swirls and wisps.
• Bake on the lowest rack until the tips of the meringue swirls start to lightly brown.

Cool and set

• Cool completely on the counter.
• Allow to set in the refrigerator before serving.