1. Prepare the Crust

1. Preheat oven to 375°F (190°C).
2. Combine flour and salt in a large mixing bowl. Cut in cold butter until the mixture resembles coarse crumbs.
3. Gradually add ice water, mixing gently until the dough forms a ball. Roll out on a floured surface and fit into a 9-inch pie pan.
4. Blind bake the crust: Prick the bottom with a fork, line with parchment paper, and fill with pie weights. Bake for 15 minutes, then remove weights and bake for another 5 minutes. Cool completely.

2. Make the Lemon Filling

1. In a saucepan, whisk sugar and cornstarch. Gradually stir in water and cook over medium heat until thickened and bubbly.
2. Remove from heat and temper the egg yolks by adding a small amount of the hot mixture to them, stirring constantly. Return the mixture to the saucepan.
3. Stir in lemon juice, zest, and butter. Cook for 2–3 more minutes, then pour into the baked crust.

3. Whip the Meringue

1. Beat egg whites and cream of tartar on medium speed until soft peaks form. Gradually add sugar, beating until glossy and stiff peaks appear.
2. Spread the meringue over the warm lemon filling, ensuring it touches the crust edges to seal. Use the back of a spoon to create peaks.

4. Bake the Pie

1. Bake at 350°F (175°C) for 10–15 minutes, or until the meringue is golden brown.
2. Cool completely at room temperature before slicing and serving.