Make crust: mix flour, salt, sugar. Cut in cold butter. Add ice water. Chill 30 minutes.
Roll out dough. Place in 9-inch pie dish. Crimp edges.
Blind bake at 375°F (190°C) for 15 minutes with weights, then 10–12 minutes without. Cool.
Make filling: whisk sugar, cornstarch, salt, and water in a saucepan. Cook until thick and boiling.
Temper egg yolks with hot mixture. Return to pan. Cook 2 minutes.
Stir in butter, lemon juice, and zest. Pour into cooled crust.
Make meringue: beat egg whites and cream of tartar to soft peaks. Gradually add sugar. Beat to stiff glossy peaks. Add vanilla.
Spread meringue over hot filling. Seal to crust edges. Create peaks.
Bake at 350°F (175°C) for 10–12 minutes until golden.
Cool 1 hour at room temp, then chill 2+ hours before slicing.