Step 1: Preheat your oven to 300°F (150°C) and line a large baking sheet with parchment paper.
Step 2: In a perfectly clean glass bowl, whisk the egg whites on medium speed until soft peaks form.
Step 3: Gradually add the superfine sugar one tablespoon at a time, whisking on high speed until the mixture is thick, glossy, and no longer feels gritty between your fingers.
Step 4: Gently fold in the white vinegar and cornstarch using a rubber spatula to stabilize the meringue.
Step 5: Spoon the meringue onto the prepared baking sheet, forming a circle about 8 inches wide with a slight dip in the center.
Step 6: Place in the oven and immediately reduce the temperature to 250°F (120°C). Bake for 90 minutes until the outside is firm.
Step 7: Turn off the oven and allow the meringue to cool completely inside with the door slightly ajar for at least 3 hours or overnight.
Step 8: While the meringue cools, peel and segment two of the blood oranges, removing all pith.
Step 9: In a chilled bowl, whip the heavy cream with vanilla extract until soft peaks form.
Step 10: Carefully transfer the cooled meringue to a serving plate and fill the center with the whipped cream.
Step 11: Drizzle the blood orange curd over the cream and arrange the fresh orange segments on top. Garnish with mint.