Preheat oven to 325 F. Line a baking sheet with parchment paper.
For Meringue: In a large bowl, beat egg whites with salt until soft peaks form when the whisk is lifted. Gradually beat in superfine sugar and continue to beat until mixture is glossy and very thick and stiff peaks form when the whisk is lifted. Beat in cornstarch and vinegar.
For individual meringues, use a large spoon to make 6-8 mounds of egg mixture on a prepared pan, allowing 1-2 inches between them. For a large meringue, spoon into a single large mound and swirl top with fork or icing spatula.

 

Bake for 2 minutes, and then reduce oven temperature to 250 F. Continue to bake until crisp to the touch, about 1 hour for individual meringues and 1 hour 40-50 minutes for the large meringue. Turn off oven and leave meringues in the oven to cool completely, about 2 hours. Store in an airtight container up to 1 week.

 

Boil strawberry kiwi juice in a saucepan over medium-high heat until reduced to 2/3 cup. Cover and chill thoroughly, at least 2 hours. It must be very cold before adding cream. In a bowl, whip cream until soft peaks are formed. Fold in reduced juice and powdered sugar. Cover and chill until ready to serve.

 

Top meringue with flavored cream and sprinkle with diced kiwi. Garnish with fresh strawberries.