01 - Preheat the oven to 375°F.
02 - Combine flour and salt in a bowl. Cut in cold, cubed butter until mixture resembles coarse crumbs. Gradually add ice water, stirring until dough just holds together. Form into a disk, wrap in plastic, and chill for 30 minutes.
03 - Roll out chilled dough on floured surface to fit a 9-inch pie dish. Trim and crimp edges. Prick base with fork. Line with parchment paper and fill with pie weights or dried beans. Bake for 15 minutes, remove weights and parchment, then bake an additional 10 minutes until golden. Cool completely.
04 - Whisk sugar, cornstarch, and salt in a saucepan. Gradually stir in water, lemon juice, and zest. Cook over medium heat, stirring constantly, until mixture thickens and bubbles.
05 - Beat egg yolks in a bowl. Slowly add a small amount of hot lemon mixture to temper the yolks, then return all to saucepan. Cook an additional 2 minutes while stirring. Remove from heat and stir in butter. Pour filling into cooled crust.
06 - Beat egg whites and cream of tartar in a clean bowl until soft peaks form. Gradually add sugar, beating until stiff, glossy peaks develop. Fold in vanilla extract.
07 - Spread meringue evenly over hot lemon filling, sealing edges to crust. Decoratively swirl the surface.
08 - Bake at 375°F for 10 to 12 minutes until meringue is golden brown.
09 - Allow pie to cool completely at room temperature, then refrigerate for at least 2 hours before slicing.