Preheat oven to 375°F (190°C).

Make the crust: In a food processor, pulse flour and salt. Add cold butter and pulse until coarse crumbs form. Gradually add ice water, pulse until dough forms. Flatten dough disk, wrap, and chill 1 hour.

Roll dough on floured surface and fit into 9-inch pie plate. Prick bottom with fork. Line with parchment and fill with pie weights or dried beans. Bake 15 minutes. Remove weights and bake 5 minutes more until crust is golden. Cool.

For the filling: In saucepan, whisk sugar and cornstarch. Gradually add water and lemon juice, stirring until smooth. Cook over medium heat until thick and bubbly.

Temper egg yolks by adding a small amount of hot mixture, then return egg yolks to saucepan. Cook 2 more minutes, stirring constantly. Remove from heat; stir in butter and lemon zest. Pour into cooled crust.

For meringue: Beat egg whites and cream of tartar until soft peaks. Gradually add sugar, beating until stiff glossy peaks form.

Spread meringue over lemon filling, sealing edges to crust to prevent shrinkage.

Bake 10-12 minutes or until meringue is golden brown. Cool completely before slicing.