Preheat oven to 150°C. Put egg whites in a mixing bowl. Use an electric mixer to beat until soft peaks form.
Add sugar gradually beating well. Sift cornflour over the mixture. Add vinegar, essence and grated orange rind. Fold through lightly to mix.
Line 2 baking trays with nonstick baking paper. Shape the mixture into small rounds on the baking trays. Place the meringue in the oven. Reduce the temperature to 120°C and bake for 30-35 minutes. Once the meringue rounds dry, turn off the oven temperature and leave them to cool in the oven.