01 - Preheat oven to 350°F.
02 - Combine graham cracker crumbs, sugar, melted butter, and salt in medium bowl. Stir until mixture resembles wet sand. Press evenly into bottom and up sides of 9-inch pie dish.
03 - Bake crust for 10 minutes. Let cool on wire rack.
04 - Whisk together sugar, cornstarch, and salt in medium saucepan. Gradually whisk in water until smooth. Cook over medium heat, stirring constantly, until mixture thickens and comes to gentle boil, about 5 minutes.
05 - Lightly beat egg yolks in small bowl. Slowly whisk in about ½ cup hot mixture to temper, then return egg yolk mixture to saucepan. Cook, stirring, for 2 more minutes.
06 - Remove from heat. Stir in lemon juice, lemon zest, and butter until smooth. Pour filling into cooled crust.
07 - Beat egg whites and cream of tartar with electric mixer until soft peaks form. Gradually add sugar and continue beating until stiff, glossy peaks form. Beat in vanilla.
08 - Spread meringue over hot lemon filling, ensuring it touches crust to seal. Swirl top decoratively.
09 - Bake pie for 12–15 minutes until meringue is golden brown. Cool completely, then chill for at least 2 hours before serving.