Heat oven to 180C/350F. Line a baking sheet with parchment paper, and draw a circle on the paper using an 8-inch cake pan as a guide. Flip the parchment over so the pencil marking is facing down (this ensures that the pencil won't transfer to the meringue).
In bowl of an electric mixer, combine egg whites (5) and salt (1/4 tsp). Begin beating at low speed, slowly increasing to high. Continue until satiny peaks begin to form. Gradually beat in sugar (1 cup) a tablespoon at a time until meringue is stiff and shiny. Rub a little of the fluff between your fingers, there should be no sugar grit—that means it is ready.
Sprinkle in cornstarch (1 tbsp), vanilla (1/2 tsp), and vinegar (1 tsp) and beat on low for 5-7 seconds until just mixed through.
Mound onto parchment paper within circle, and shape into a disk, flattening top and smoothing sides. Coax it into a dome shape with edges sloping in slightly. Flatten top so it's 4-5cm high, not much higher. It will rise/expand.
Place in oven, and immediately reduce the oven temperature 110C/230F (fan/convection) or 125C/255F (standard). Bake for 1 hour 20 minutes. Turn off heat, and allow meringue to cool completely in oven, about 3-4 hours.
Topping
In a mixing bowl, combine cream (1 cup), sugar (2 tbsp), and vanilla (1 tsp). WHip until firm and smooth. Don't over-whip.
To serve, carefully peel off parchment and place meringue on a platter. Spoon the cream over the meringue and top with your choice of fruit. Strawberries, blood oranges, passionfruit, kiwi, blueberries, and raspberries all work well.