Preheat your oven to 350°F (175°C).

Prepare the pie crust in a pie dish and bake according to package instructions until golden brown.

In a saucepan, combine sugar, cornstarch, and salt.

Gradually add water to the dry mixture, stirring constantly over medium heat.

Once the mixture thickens, remove from heat.

In a separate bowl, whisk the egg yolks and gradually add a small amount of the hot mixture to temper them.

Return the tempered yolks to the saucepan and stir in lemon juice and zest.

Cook for an additional 2-3 minutes, then remove from heat and add butter.

Pour the lemon filling into the baked crust.

In a clean bowl, whip egg whites and cream of tartar until soft peaks form, then gradually add sugar to form stiff peaks.

Spread the meringue over the lemon filling, ensuring it touches the crust to prevent shrinking.

Bake for 10-12 minutes until the meringue is golden brown.