Step 1: Preheat your oven to 150°C (300°F). Line a large baking sheet with parchment paper and draw an 8-inch circle on the paper as a guide, then flip the paper over.
Step 2: In a clean, grease-free glass or metal bowl, whisk the egg whites on medium speed until soft peaks form.
Step 3: Gradually add the caster sugar one tablespoon at a time, whisking constantly on high speed until the meringue is thick, glossy, and the sugar has completely dissolved.
Step 4: Gently fold in the white vinegar, cornstarch, and vanilla extract using a spatula, being careful not to deflate the mixture.
Step 5: Pile the meringue onto the prepared parchment paper within the circle guide. Use a spatula to smooth the sides and create a slight indent in the center for the toppings.
Step 6: Lower the oven temperature to 120°C (250°F) and bake for 90 minutes. Turn off the oven and leave the pavlova inside with the door slightly ajar until completely cool.
Step 7: Once cooled, whip the heavy cream until soft peaks form. Spread the cream over the center of the meringue.
Step 8: Top with fresh mango slices and drizzle the passionfruit pulp over the entire dessert just before serving.