Preheat the oven to 250°F and line a large baking sheet with foil or parchment.
In a small bowl or measuring cup, stir together the sugar and cornstarch to get rid of any lumps. In a large glass or stainless steel bowl, beat the egg whites with an electric mixer until soft peaks form. Gradually add the sugar mixture, beating constantly until the mixture holds stiff, glossy peaks – it should have the consistency of stiff shaving cream. Beat in the vinegar and vanilla.
Spoon a mound (or mounds) of meringue onto the baking sheet and spread it/them out with a spatula or back of a spoon, forming nests—make one large pavlova, two medium, four medium-small or even bite-sized pavlova, making little indents in the middle using the tip of a teaspoon. Bake for 1 hour (no matter the size), until crisp and dry. Let the meringues cool completely.
Meanwhile, toss the cherries with almost all the sugar (hold back a couple teaspoons to sweeten the cream) and warm them for a minute in the microwave to help them release their juices without softening them completely. Beat the cream with the remaining sugar and vanilla until softly stiff.
?To assemble, peel the pavlovas off the parchment and place on a serving tray or platter, top with whipped cream and whatever fruit you like. Fresh mint also looks nice. Serve within half an hour or so. Serves 8ish.