Preheat oven to 200°C (400°F) fan forced. Line a tray with aluminium foil and spray the foil lightly with cooking spray.
Place egg whites into a large bowl and bring to room temperature.
In a separate bowl, mix cornflour and sugar together.
Add sugar mixture to egg whites, along with salt and boiling water all at once.
Beat on high speed until sugar dissolves and mixture holds its shape a little, then pause beating to add vinegar and vanilla essence. Continue beating until the mixture is stiff and stiff peaks form.
Pile the mixture onto the prepared tray, shaping it into the size of a sponge cake.
Immediately reduce oven temperature to 145°C (300°F) and bake for about 1 hour.
About 5 minutes before the pavlova finishes baking, place your serving plate in the sink and pour boiling water over it. Let it sit for a couple of minutes, then dry it well. A hot plate helps the pavlova sink slightly in the middle when inverted, making the perfect space for cream and fruit.
Once baked, carefully flip the pavlova onto the warm plate and gently remove the foil.
Let the pavlova cool completely (it will sink in the middle). and may crack, but that is completely normal.
Whip cream until soft peaks form. No need to add icing sugar, the pavlova is sweet enough.
Spoon whipped cream onto the pavlova and decorate with fresh fruit.