Pre-bake a 9" pie crust until golden brown

Use a microplane grater/ zester and zest approximately 2-3 lemons to make 1 tablespoon of lemon zest

Juice 2-3 lemons (more if needed) to get ½ cup of lemon juice

Separate 4 large eggs. Place whites in large mixing bowl to be used with the electric mixer, place yolks in a small mixing bowl

Preheat the oven to 350°F, place the rack in the center of the oven.

Whisk together sugar, flour, cornstarch, and salt in a medium non-reactive saucepan

Add water, lemon juice, and lemon zest to sugar mixture. Mix together.

Heat the lemon mixture until bubbling, stirring constantly with a non-reactive utensil. Add butter, boil and stir for 1 minute. Remove from heat.

Temper the egg yolks by VERY slowly pouring about ½ cup (more won't hurt) of the hot lemon mixture into the egg yolks while stirring continuously.

Pour the tempered egg yolk mixture into the saucepan with lemon filling. Heat over medium heat, stirring continuously until mixture reaches full boil. Boil for 2 minutes while stirring, remove from heat

Pour lemon mixture into the pre-baked pie crust, set aside. (I like to pour the mixture through a sieve to remove the lemon zest)

In a large mixing bowl, add egg whites and cream of tartar, whip using medium-high speed until the cream of tartar is dissolved into the egg whites and the mixture is foamy

With the mixer still going, add 1 tablespoon of sugar to the foamy egg whites and continue whipping, turn the mixer up to high speed

Continue adding the sugar 1 tablespoon at a time giving each tablespoon time to be incorporated before adding the next

Whip until the meringue holds a stiff peak.

Heap the meringue onto the center of the pie filling. Use an offset spatula to spread the meringue to the edges of the pie and seal it to the crust. Seal the meringue all the way around the pie, leaving no filling showing.

Make swirls and peaks in the meringue with the spatula for decoration.

Place the pie in the oven for 7-10 minutes until toasted a light golden brown. Carefully watch the pie during the last few minutes as the meringue will quickly burn once if left too long.