Preheat the oven to 350°F.

In a mixing bowl, combine flour, butter, sugar, and salt. Mix until the mixture resembles coarse crumbs.

Gradually add ice water, one tablespoon at a time, mixing until the dough holds together. Form into a disk, wrap in plastic wrap, and chill for 30 minutes.

Roll out the chilled dough on a floured surface to fit a 9-inch pie pan. Place the dough in the pan, trim the edges, and prick the bottom with a fork.

Bake for 15-20 minutes or until lightly golden. Remove from the oven and let cool.

In a saucepan, combine 1 cup sugar, cornstarch, and salt. Gradually whisk in water. Cook over medium heat, stirring constantly until the mixture thickens and bubbles.

Reduce heat and stir a small amount of the hot mixture into the egg yolks, then return to the saucepan. Cook for 2 more minutes, stirring constantly.

Remove from heat and stir in butter, orange zest, orange juice, and vanilla extract. Pour the filling into the cooled pie crust.

In a clean mixing bowl, beat egg whites and cream of tartar until soft peaks form. Gradually add ½ cup sugar, continuing to beat until stiff peaks form.

Spread the meringue over the orange filling, sealing the edges to prevent shrinking.

Bake the pie in the preheated oven for 10-12 minutes or until the meringue is golden brown.

Allow to cool at room temperature for at least 1 hour before serving.