1 (9 inch) pie crust, baked
1 cup white sugar
2 tablespoons all-purpose flour
3 tablespoons cornstarch
1/4 teaspoon salt
1 1/2 cups water
2 lemon, juiced and zested
4 egg yolks, beaten
2 tablespoons butter
4 egg whites
6 tablespoons white sugar

Preheat oven to 350 degrees F (175 degrees C).

To Make Lemon Filling: In a medium saucepan, combine 1 cup sugar, flour, cornstarch, and salt. Mix in water and lemon juice. Cook over medium-high heat, stirring frequently, until mixture comes to a boil. Stir in butter. Place egg yolks in a small bowl and gradually whisk in 1/2 cup of hot sugar mixture. Whisk egg yolk mixture back into remaining sugar mixture. Bring to a boil while stirring constantly. Boil and stir until thick. Remove from heat. Pour filling into baked pastry shell.

To Make Meringue: In a large glass or metal bowl, whip egg whites until foamy. Add sugar gradually while continuing to whip, until egg whites form stiff peaks. Spread meringue over pie, covering lemon filling completely.

Bake in preheated oven for 10 minutes, until meringue is golden brown.