Step 1: Prepare Your Equipment and Oven. Preheat your oven to 250°F (120°C). Line two large baking sheets with parchment paper. Draw 24 circles, about 2-3 inches in diameter, on the parchment paper, leaving space between each. Flip the paper over so the pencil marks are on the underside.
Step 2: Whip the Egg Whites. In a very clean, grease-free stand mixer bowl (or a large glass bowl with a hand mixer), beat the room-temperature egg whites on medium speed until soft peaks form. This might take 3-5 minutes.
Step 3: Gradually Add Sugar. With the mixer still running on medium speed, gradually add the superfine sugar, one tablespoon at a time, allowing each addition to fully incorporate before adding the next. Continue beating on high speed until the meringue is glossy, thick, and stiff peaks form. When you rub a small amount between your fingers, you shouldn’t feel any sugar granules.
Step 4: Fold in Remaining Ingredients. Gently fold in the cornstarch, white vinegar, and vanilla extract using a rubber spatula. Be careful not to deflate the meringue.
Step 5: Pipe the Meringues. Transfer the meringue to a large piping bag fitted with a star tip (or a round tip). Pipe the meringue into the drawn circles on the parchment paper, building up the sides slightly to create a nest-like shape. Alternatively, you can use a spoon to dollop and shape them.
Step 6: Bake and Cool. Place the baking sheets in the preheated oven. Immediately reduce the oven temperature to 200°F (95°C). Bake for 1 hour and 30 minutes. After baking, turn off the oven and leave the pavlovas inside with the door ajar for at least 1 hour, or until completely cool. Do not open the oven door during baking or cooling, as sudden temperature changes can cause cracking.
Step 7: Prepare Whipped Cream. In a chilled bowl, beat the heavy cream and powdered sugar on medium-high speed until firm peaks form.
Step 8: Assemble and Serve. Carefully peel the cooled meringue shells from the parchment paper. Place a dollop of whipped cream onto each meringue. Garnish generously with fresh cranberries, pomegranate seeds, and a few mint leaves. Serve immediately.