Key Lime Pie

For the Filling

• 1 1/2 cups granulated sugar
• 6 tablespoons cornstarch
• 1 1/2 cups water
• 1/3 cup fresh lime juice
• 3 large egg yolks
• 1 1/2 teaspoons grated lemon zest
• 2 teaspoons white vinegar
• 3 tablespoons unsalted butter
• 1 baked 9-inch pie shell

For the Meringue

• 1 tablespoon corn starch
• 2 tablespoons cold water
• 1/2 cup boiling water
• 3 large egg whites
• 6 tablespoons granulated sugar
• 1 teaspoon vanilla extract
• Pinch of salt 

1. Combine the sugar and cornstarch in the top of a double boiler. Add the water and stir to combine. In a medium bowl, whisk the lime juice and egg yolks until well mixed; add to the cornstarch mixture and whisk until blended. Place the double boiler over 1 inch of boiling water and cook, stirring, until the mixture is thick and no starchy taste remains, about 25 minutes. Turn off the heat and remove the mixture from the hot water; let cool slightly. Whisk in the grated lime zest, vinegar and butter until completely incorporated. Pour the mixture into the pie shell; cover with plastic wrap and chill in the refrigerator until cold.

Meringue

1. Preheat the oven to 350 degrees F. In a small saucepan combine the cornstarch and cold water; whisk until blended; add the boiling water and place over medium heat. Cook, stirring, until the mixture is clear and thickened. Remove from the heat and let stand until completely cold. In a large grease-free mixing bowl beat the egg whites with an electric mixer on medium speed until frothy. Increase the speed and gradually add the vanilla and salt; gradually beat in the cornstarch; increase the speed to high and beat until all the ingredients are fully incorporated. Spread the meringue over the cooled pie filling and bake for 10 minutes, or until the top is lightly browned.