Mix the 2/3 cup of granulated sugar with the 3 tablespoons of cornflour and set aside. Measure out the 3 teaspoons of lemon juice and set aside.
Beat the egg whites with salt till soft peaks start forming - this should take about 3 minutes. (I use a handheld mixer as I don't have a stand mixer at the moment and it works just as well. In fact the picture attached to this recipe was made with my hand held beaters.)
Add castor sugar 2 tablespoons at a time and continue beating for another 7 mins.
The meringue should be glossy and quite strong: ie: not light texture like whipped cream.
Now fold through alternatively the granulated sugar and cornflour mixed with the lemon juice. What this does is provide the dual textures of a pavlova - crunchy outside and soft marshmallow inside.
Line a tray with baking paper and using a large serving spoon make a base of pavlova mix. Then using the spoon make the edges of the pavlova by putting spoonfuls around the edge. You can experiment with whether you want a smooth edge using a palette knife or free form like the picture and just placing spoonfulls around the edge.
You can also pipe this meringue successfully into smaller nests or even mini meringues.
Bake in a very slow oven (110C/220F) for 2 hrs. Turn off the oven and allow the pavlova to cool slowly overnight if possible but it is not crucial.