Vinegar Pie

Despite its name, this is a good, sweet pie.

2 eggs, separated, at room temperature
1 tablespoon butter
1 cup plus 2 tablespoons sugar, divided
2 tablespoons cornstarch
1 cup boiling water
2 tablespoons apple cider vinegar
1 teaspoon fresh lemon juice
1/4 teaspoon cream of tartar
1/2 teaspoon vanilla extract
1 baked 9-inch piecrust

Preheat oven to 350°F. In a heavy saucepan, combine the egg yolks, butter, 1 cup of the sugar and cornstarch. Stir in the boiling water and vinegar. Cook over low-medium heat, stirring constantly, until mixture thickens. Stir in lemon juice. Pour filling into baked 9-inch piecrust.

Beat the egg whites until foamy. Continue beating, gradually adding the 2 tablespoons sugar, cream of tartar and vanilla, until stiff peaks form.

Spread meringue over hot filling, sealing to edges. Bake for 12 to 15 minutes until meringue is lightly browned.