Preheat oven to 150C/300F. Prepare a pan (minimum 30cm diameter) with baking paper.
Beat egg whites and cream of tartar in a large bowl with an electric mixer until soft peaks form. Gradually add sugar, beating until dissolved between additions, until mixture is thick and glossy. Using a spatula, fold in extra sifted corn flour.
Spoon meringue into the centre of the plate. Using a spatula, spread the meringue into a 23cm round, making a shallow well in the centre.
Reduce oven to 100C/200F.
Bake pavlova in the lower half of the oven for 1 1/2 hours or until dry and crisp. Turn off the oven and cool in oven with the door ajar.
Beat cream in a small bowl with an electric mixer until soft peaks form.
Carefully transfer pavlova to a serving platter. Top with cream, strawberries, mango and passionfruit.