Preheat oven at 130°C/265°F. Line a baking sheet with parchment paper and draw a 15cm circle in the middle.
Beat egg whites and salt until soft peaks form. Reduce the speed of the mixer and add the water and sugar. Increase the speed again and beat for 5-7 minutes until stiff peaks form. Fold in vanilla, lemon or vinegar and cornstarch, mixing gently until well- combined.
Spread the meringue onto the prepared baking sheet to fill the circle, using the spatula to shape it.
Bake for 1 hour. Reduce the temperature to 110°C/235°F and bake for another 40 minutes. Turn off the oven and let meringue sit inside with the door closed for 1 ½ hours.
Fill the Pavlova with lemon curd, whipped cream and fresh fruit.