Preheat the oven to 225F. Line a large baking pan with parchment paper.
In a dry bowl, beat the egg whites for about 3 minutes. With the mixer on high, gradually add in the sugar a little bit at a time until stiff and glossy peaks form— about 7 minutes.
Sift the cornstarch into the meringue and pour in the vinegar and vanilla. Using a rubber spatula, carefully, so as to not deflate the egg whites, fold the ingredients into the meringue until no streaks of vanilla remain.
Spoon the meringue into a piping bag and pipe 12 circles. You want them to have a good height, maybe around 2 inches. Using a spoon, create a slight dent in the center of each meringue to hold your toppings.
Bake for about 1 hour and 15 minutes or until the meringue is firm to the touch and a pale cream color, they should not be sticky. Turn the oven off and leave the oven door closed, allowing the meringue to cool down in the oven for about 30 minutes.
Beat together the heavy cream and sugar until soft peaks form, about 2 minutes. Top the mini meringues with whipped cream and garnish with lemon curd or fruit of your choice! Serve immediately!