Preheat the oven to 180°C/160°C Fan/350°F and line a baking sheet with baking parchment.
In a grease-free stand mixer bowl, whisk the egg whites until firm peaks form.
Then beat in the sugar a spoonful at a time until the meringue is stiff and shiny.
Be patient: it takes a little time to thicken glossily.
Sprinkle the cornstarch and vinegar over the meringue, then, by hand, gently fold everything until it is thoroughly mixed in.
Mound onto the lined baking sheet in a fat disc approximately 22cm/9inch in diameter, smoothing the sides and top.
Place in the oven, then immediately turn the temperature down to 150°C/130°C Fan/300°F and bake for 1 hour.
Take out of the oven and leave to cool, but do not leave anywhere cold as this will make it crack too dramatically.
You’ll always get some cracks though, so don’t fret.
If you think your kitchen is too cold, then drape the pavlova base loosely with a clean tea towel.
When the meringue is completely cooled, turn the pavlova base onto a large flat plate with the underside uppermost.