01 - Combine flour, sugar, and salt in a bowl. Cut in the cold butter until the mixture resembles coarse crumbs. Gradually add ice water, mixing just until the dough forms. Shape into a disc, wrap tightly, and refrigerate for 30 minutes.
02 - Preheat the oven to 375°F. Roll out the dough on a floured surface and press into a 9-inch pie dish. Trim and crimp edges. Prick the bottom with a fork, line with parchment paper, and fill with pie weights or dried beans. Bake for 15 minutes, then remove weights and parchment, and bake an additional 10 to 12 minutes until golden. Cool completely.
03 - In a saucepan, whisk together sugar, cornstarch, and salt. Gradually add water, whisking until smooth. Cook over medium heat, stirring constantly, until the mixture thickens and bubbles, about 5 to 7 minutes.
04 - Beat egg yolks in a small bowl. Slowly whisk in 1/2 cup of the hot lemon mixture to temper the yolks. Return yolk mixture to the saucepan and cook for 2 additional minutes, stirring constantly.
05 - Remove the saucepan from heat. Stir in lemon juice, lemon zest, and butter until smooth. Pour the filling into the cooled crust.
06 - In a clean bowl, beat egg whites with cream of tartar until soft peaks form. Gradually add sugar while continuing to beat until stiff, glossy peaks develop. Beat in vanilla extract.
07 - Spread the meringue over the hot lemon filling, sealing the edges to the crust to prevent shrinking. Bake at 350°F for 12 to 15 minutes, or until the meringue turns golden brown.
08 - Allow the pie to cool at room temperature for 1 hour. Refrigerate for at least 1 hour before slicing and serving.