Preheat your oven to 325°F (163°C).
Place the graham cracker crust in the pie plate if you didn't buy premade.
In a large bowl, whisk together sweetened condensed milk, lemon juice, and grated lemon rind.
Blend in the egg yolks until smooth.
Pour the filling into the pie crust.
In a medium bowl, beat the egg whites and cream of tartar with an electric mixer until soft peaks form.
Gradually add sugar and continue to beat until stiff peaks form.
Spread the meringue evenly over the filling, covering it completely.
Bake in the preheated oven for 12 to 15 minutes or until the meringue is golden brown.
Allow the pie to cool to room temperature.
Refrigerate for at least 4 hours before serving to allow the filling to set.
