Preheat oven to 275°F (135°C) and line a baking sheet with parchment paper.
Draw 6-8 circles (3-4 inches) on parchment and flip it over.
Beat egg whites on medium speed until soft peaks form. Add salt.
Gradually add sugar, one tablespoon at a time, beating on medium-high speed.
Beat until glossy and stiff peaks form (8-10 minutes). Check for dissolved sugar.
Gently fold in cornstarch, vinegar, and vanilla extract using a spatula.
Spoon or pipe meringue onto prepared parchment, forming small nests.
Place in oven and immediately reduce temperature to 250°F (120°C).
Bake for 1 hour, then turn off oven and let pavlovas cool inside overnight.
Before serving, whip cream with powdered sugar and vanilla until soft peaks form.
Top pavlovas with whipped cream, fresh fruits, and optional mint garnish.