Preheat the oven to 350°F (175°C). In a mixing bowl, combine flour, butter, and sugar until crumbly. Add egg yolk and cold water, mix until dough forms. Roll out and place in pie dish.

Bake the crust for 15 minutes or until golden. Remove from oven and let cool.

In a saucepan, combine sugar and cornstarch. Gradually whisk in water and cook over medium heat until thickened. Remove from heat.

Whisk in egg yolks, lemon juice, lemon zest, and butter. Pour the filling into the baked crust.

In a mixing bowl, beat egg whites and cream of tartar until soft peaks form. Gradually add sugar and continue beating until stiff peaks form.

Spread meringue over the lemon filling, sealing the edges. Bake for an additional 10 minutes or until meringue is golden.