Preheat your oven to 350°F (175°C). In a mixing bowl, whisk together flour, sugar, and salt. Cut in butter until coarse crumbs form. Gradually add ice-cold water until a dough forms.

Refrigerate the dough for 30 minutes, then roll it out and fit into a pie plate. Prick the bottom, freeze for 10-15 minutes, and bake for 15 minutes or until lightly golden.

For the filling, whisk together sugar, cornstarch, and salt in a saucepan. Gradually stir in lemon juice, water, and zest. Cook over medium-high heat until boiling, stirring constantly.

Boil for 2 minutes until thickened. Temper in egg yolks, cook for an additional 2 minutes, then stir in butter until smooth and pour into cooled crust.

For the meringue, beat egg whites until frothy, add cream of tartar and salt, and beat to soft peaks. Gradually add sugar and beat until stiff, shiny peaks form, then mix in vanilla.

Spread meringue over the hot lemon filling, sealing to the crust edges. Bake for 10-12 minutes or until meringue is golden brown.

Let it cool at room temperature for about 1 hour, then refrigerate until fully chilled, ideally for 2 hours before serving.