Filling: Whisk sugar, lemon juice, water, cornstarch, and salt together

in large nonreactive saucepan until cornstarch is dissolved. Bring to

simmer over medium heat, whisking occasionally, until mixture becomes

translucent and begins to thicken, about 5 minutes. Whisk in yolks until

combined. Stir in zest and butter. Bring to simmer and stir constantly

until mixture is thick enough to coat back of spoon, about 2 minutes.

Strain through fine-mesh strainer into pie shell and scrape filling off

underside of strainer. Place plastic wrap directly on surface of filling

and refrigerate until set and well chilled, at least 2 hours and up to 1

day.

Weep No More Meringue: Adjust oven rack to middle position and heat oven

to 400 degrees. Combine water and sugar in small saucepan. Bring to

vigorous boil over medium-high heat. Once syrup comes to rolling boil,

cook 4 minutes (mixture will become slightly thickened and syrupy).

Remove from heat and set aside while beating whites.

With electric mixer, beat whites in large bowl at medium-low speed until

frothy, about 1 minute. Add salt and cream of tartar and beat, gradually

increasing speed to medium-high, until whites hold soft peaks, about 2

minutes. With mixer running, slowly pour hot syrup into whites (avoid

pouring syrup onto whisk or it will splash). Add vanilla and beat until

meringue has cooled and becomes very thick and shiny, 5 to 9 minutes.

Using rubber spatula, mound meringue over filling, making sure meringue

touches edges of crust. Use spatula to create peaks all over meringue.

Bake until peaks turn golden brown, about 6 minutes. Transfer to wire

rack and cool to room temperature. This pie is best served on the day it

is made.

Notes:

NOTES : Juice about 6 lemons.