Preheat and Prep:
Preheat oven to 250°F (120°C).
Line a baking sheet with parchment paper. Draw an 8-inch circle on the paper as a guide, then flip it over so the pencil side is down.
Make the Meringue:
In a clean, dry mixing bowl, beat egg whites with an electric mixer on medium speed until soft peaks form.
Gradually add sugar, 1 tablespoon at a time, while continuing to beat until glossy stiff peaks form (about 7–8 minutes).
Add vinegar (or lemon juice), cornstarch, and vanilla extract. Beat gently until just combined.
Shape the Pavlova:
Spoon the meringue onto the parchment circle, spreading it out and creating a slight indentation in the center for the toppings.
Bake:
Place in the oven and immediately reduce temperature to 225°F (110°C).
Bake for 1 hour 15 minutes until crisp and dry on the outside.
Turn off the oven, crack the door slightly, and let the Pavlova cool completely inside the oven to prevent cracking.
Make the Whipped Cream:
Beat the heavy cream, powdered sugar, and vanilla until soft peaks form.
Assemble and Serve:
Just before serving, spread whipped cream over the cooled meringue.
Top with fresh fruit and serve immediately.