First, prepare and blind bake your pie crust until lightly golden. This step prevents a soggy bottom and ensures a crisp, flaky base. Let it cool slightly before adding the filling.
In a saucepan, whisk together water, sugar, cornstarch, and salt. Cook over medium heat until thick and bubbling. Slowly temper in the egg yolks
Beat egg whites and cream of tartar until soft peaks form. Gradually add sugar while mixing until stiff, glossy peaks develop. Spread the meringue over the warm lemon filling, making sure it touches the crust edges to seal.
Bake until the meringue is golden brown on top. Allow the pie to cool at room temperature, then refrigerate for several hours to fully set before slicing.