Preheat oven to 350°F (177°C). Line a baking sheet with parchment paper.
Beat egg whites and vinegar in a clean bowl until soft peaks form (about 2 minutes.)
Add the sugar. Beat until the egg whites become glossy and stiff (about 30 more seconds.)
Add the vanilla and cornstarch and beat another 30 seconds.
Gently spoon the meringue into 8 mounds on the parchment-lined baking sheet. Press an indent into the centre of each meringue, allowing the sides to come up higher to contain the toppings.
Place the sheet of meringues into the oven. Immediately turn the oven temperature down to 200°F. Bake them for 90 minutes, keeping the oven door closed. Then, without opening the oven, turn off the heat and allow the meringues cool.
Store cooled meringues in a tightly covered container at room temperature.
Mini Pavlova Assembly
Place a meringue onto each serving plate.
Scoop some whipped cream onto each meringue base.
Spoon a rounded tablespoon of lemon curd onto each.
Top each serving with a sprinkling of fresh berries.
Both the meringues and lemon curd can be made a day or two ahead.