Pre-heat oven to 160°C / 140°C fan assisted / gas mark 3 / 320°F.
Draw a circle of 18cm (7 inches) (draw round a 7 inch round cake tin) on baking parchment.
Place the baking parchment, drawn side down on a large baking tray.
In a spotlessly clean mixing bowl pour the egg whites and whisk on a medium -low speed (setting 4 on a standard stand mixer) until thickened and formed soft peaks.
Continue whisking the egg whites and add the sugar one tablespoon at a time, waiting about 10-15 seconds between each addition of sugar. Scrape down the sides of the bowl before every tablespoon to make sure all the sugar is being whisked in. Continue until all the sugar has been added. Then continue whisking on medium – low speed for a further 5 minutes.
Check the consistency of the meringue between your fingers, it should be silky smooth without any gritty sugar. If it is still gritty then whisk for a further 5 minutes. Continue checking every 5 minutes until the meringue is silky smooth with no grainy sugar. It will be thick, smooth and glossy.
Finally add the vinegar, cornflour and salt and mix for a final 2 minutes to make sure it’s well combined.
Use a blob of meringue under each corner of the baking parchment to secure it in place to the baking tray. Spoon the meringue into the centre of the drawn circle on the baking parchment. Smooth out with a silicone spatula to the shape of the circle to form a tall cylindrical structure. Use a small palette knife to make a pattern up the sides of the meringue.
Place the meringue in the oven. Immediately turn the oven temperature down to 120°C / 100°C fan assisted / gas mark ½ / 250°F and bake for 1 ½ hours.
Check the meringue by cracking open the door a little to see, it should look crisp and dry.
Switch off the oven and leave the oven door cracked open for the meringue to cool and dry out.