Preheat oven to 300 degrees F. Line a baking sheet with parchment paper. Draw a 9-inch circle on the parchment paper.
In a large bowl, beat egg whites until stiff, but not dry. Gradually add in the sugar, 1 tablespoon at a time, beating well after each addition. Beat until thick and glossy. Overbeaten egg whites lose volumn and deflate when folded into other ingredients. Be absolutely sure not a particle of grease or egg yolk gets into the whites. Gently fold in vanilla extract, lemon juice and cornstarch.
Spoon mixture inside the circle drawn on the parchment paper. Working from the center, spread mixture toward the outside edge, building edge slightly. This should leave a slight depression in the center.
Bake 1 hour. Cool on a wire rack.
In a small bowl, beat heavy cream until soft peaks form (add sugar if desired); set aside. Remove the paper and place meringue on a flat serving plate. Fill the center of the meringue with whipped cream. Top whipped cream with kiwi fruit slices.