Preheat your oven to 300°F (150°C). Separate egg whites and let them come to room temperatureIn a large stand mixer bowl, beat the egg whites until they form stiff peaks.
Gradually add the sugar to the egg whites, one tablespoon at a time, while continuing to beat the mixture.
Once all the white sugar has been added, beat the mixture for an additional 2-3 minutes, or until it is glossy and thick.
Add the vinegar, vanilla extract, and cornstarch to the mixture, and beat for 30 seconds.
Scoop the mixture onto the prepared baking tray lined with a sheet of parchment paper
Using a spoon, pipping bag, or an ice cream scoop, to form small, round mounds. Be sure to leave some space between each mini pavlova, as they will spread during baking.
Use the back of a large spoon to create a small indentation in the center of each mini pavlova, which will later be filled with whipped cream and fruits.
Bake the mini pavlovas in the preheated oven for 1 hour, or until they are crisp on the outside and soft on the inside.
Once the pavlovas are cooked, turn off the heat and let them cool inside the oven for 4 - 10 hours.
Once the mini pavlovas are cool, carefully remove them from the baking sheet and fill them with whipped cream and fresh fruits.