Beat egg whites and sugar in a large, clean bowl with electric mixer until stiff peaks form. In separate bowl, mix together vinegar, vanilla and cornstarch until smooth. Pour cornstarch mixture into egg white mixture and beat until thick and glossy, 4 minutes.
Cover a baking sheet in parchment paper and draw an 8 inch (20 centimeter) circle in the center. Spoon or pipe mixture inside the circle, to within a little less than an inch (2 centimeters) from the edge.
Place in preheated oven, reduce temperature to 200 degrees F (100 degrees C), and bake 1 hour. Turn oven off and leave Pavlova to cool inside. Decorate cooled Pavlova with whipped cream and fruit to serve.
