Preheat the oven to 375°F (190°C). Prepare the pie crust by combining flour and salt in a food processor. Add cold butter, pulse until it resembles coarse crumbs, and add ice water to bring it together. Wrap dough in plastic wrap and chill for at least 30 minutes.

1. Roll out the dough, press it into a 9-inch pie pan, trim excess, prick with a fork, and bake for 12-15 minutes until golden brown. Let it cool.
2. For the filling, whisk together sugar, cornstarch, and salt in a saucepan. Add water and cook over medium heat, whisking until thickened and boiling. Beat egg yolks, then temper with the hot mixture and return to the pan. Cook for 2-3 more minutes, then stir in lemon juice, zest, and butter. Pour into cooled crust.
3. For the meringue, beat egg whites with cream of tartar until soft peaks form. Gradually add sugar and beat until stiff peaks form. Fold in vanilla extract.
4. Spoon the meringue onto the lemon filling, spreading to the edges to seal. Use a spoon to create peaks and swirls.
5. Bake at 375°F (190°C) for 10-12 minutes or until golden. Cool for 1 hour before slicing.
6. Serve with whipped cream if desired and enjoy!