Whisk the egg whites until stiff. Add the sugar, a 1/4 cup at a time, whisking until the meringue is very stiff. Whisk in the cornflour, vanilla and vinegar.
Pile the meringue onto a baking sheet lined with silicone or grease proof paper and spread into a 23 cm round. Hollow out the centre slightly and bake in a preheated cool oven, 150c, for 1 1/2 hours.
Cool, then remove the paper and place the pavlova on a serving dish.
Whip cream until stiff and pile onto the pavlova and top with fruit and chocolate pieces.