Pies or cakes? Lemon or chocolate? If it's pies and lemons, then this is for you!
Preheat oven to 400ºF.
In a heavy saucepan stir to combine the sugar, cornstarch, and salt.
Whisk in the water and lemon juice.
Cook over medium heat, stirring constantly, until the mixture reaches a boil.
In a small bowl, whisk the egg yolks. Add about 1/2 cup of the hot lemon/sugar mixture to the eggs. Whisk together. Then return to the hot mixture in the pan. Continue cooking until the mixture is thick(do not boil).
Remove from heat. Add the butter and lemon zest; whisk together. Cool to lukewarm.
Pour into the blind baked pie crust. Immediately spread the meringue over filling. Be sure to spread to the pie crust edges.
Bake for 10 - 15 minutes, until golden brown.
At this point, stand by the oven door and check the pie frequently! Barely open the oven door and check your pie. The meringue will look perfect one minute and can burn two minutes later.
Cool in a draft free place for 2 - 3 hours before serving.