Noooo! You don’t need the corn flour and vinegar
Just 3 large egg whites and 175g caster sugar
Then follow Delia below
For the meringue place the egg whites in a large clean bowl and whisk them until they form stiff peaks (it's very important, though, not to over-whisk the egg whites because, if you do, they will start to collapse).
Now start to whisk in the 175g sugar, about a tablespoon at a time, whisking after each addition until all the sugar is in. Now take a metal tablespoon and spoon about one third of the meringue mixture on to the prepared baking sheet, forming a circle about 20 cm in diameter.
Then spoon round blobs next to each other so that they join up to form a circle all around the edge. Now, using the tip of a skewer, make little swirls in the meringue. Pop it in the oven, then immediately turn down the heat to 140°C , gas mark 1 and leave it for 1 hour.
Then turn the heat right off but leave the Pavlova inside the oven until it's completely cold.
< completely missed point>