Preheat oven to 350°F (175°C).
In a bowl, mix flour and cold butter until crumbly. Add ice water and mix until dough forms. Roll out and fit into a pie dish. Bake for 10-12 minutes.
In a saucepan, combine sugar, cornstarch, and salt. Gradually stir in water. Cook over medium heat, stirring constantly, until mixture boils and thickens. Remove from heat.
Stir in butter, then gradually whisk in egg yolks. Return to heat and cook for 2 more minutes. Remove from heat and stir in lemon juice and zest. Pour into baked crust.
In a bowl, beat egg whites and cream of tartar until soft peaks form. Gradually add sugar, beating until stiff peaks form. Spread meringue over hot filling, sealing edges to crust.
Bake for 10-12 minutes, or until meringue is golden brown. Cool completely before serving.