Low Sugar Pavlova

Low Sugar Pavlova / Confectioners sugar for dusting, 1 cup superfine granulated sugar, 1/2 cup packed light brown sugar, 1 1/2 tablespoons cornstarch, 1 1/2 teaspoons pure vanilla extract, 2 teaspoon distilled white vinegar, 3/4 cup egg whites (from 5 to 6 large eggs) at room temperature 30 minutes.