Preheat the oven to 150°C fan forced and line 2 large baking trays with baking paper.
Place your egg whites into the bowl of a stand mixer fitted with a whisk attachment. Mix on high until the mixture has formed soft peaks.
Once soft peaks have formed, add the caster sugar one table spoon at a time, ensuring you are whisking the mixture constantly during this step.
Keep whisking until the sugar has dissolved. This will take some time so be patient.You can test the mixture by rubbing it between two fingers and if you don't feel any sugar granules it is done.
Add the cornflour and mix for 1 minute to combine.
Add the vinegar and vanilla and mix to combine.
Spoon large dollops of the mixture onto the your baking trays and shape into approx 10cm rounds. I made a slight well in the centre of my pavlovas to maximise toppings that will fit in for later.
Place in the oven and immediately reduce the oven temperature to 110°C. Bake for 30-40 minutes.Baking time always varies on how large you make your pavlovas so if you make smaller pavs, reduce the cooking time. If you make larger pavs, increase the cooking time.
The pavlovas are done when the outside is firm and crisp so you can check at the earlier time mark listed above and judge from there. Once they are done, turn the oven off and leave the pavlovas in the oven to dry out. I place a wooden spoon in the oven door to keep it ajar slightly. Let them cool in the oven for at least 1 hour.