Preheat the oven to 275°F (135°C) with a rack in the center position. Using a pencil and bottom of cake pan or plate, trace a 9-inch (23-cm) circle in the center of a large piece of parchment paper. Set the parchment paper - pencil side facing down - into a half sheet pan.
Prepare Raspberry Curd: Combine the raspberries, egg yolks, sugar, unsalted butter, lemon juice, cornstarch, and salt in a medium saucepan and stir together. Set over medium heat until the mixture begins to bubble. Boil, stirring frequently, for 2 to 3 minutes, cooking until the curd has reduced, thickened, and the cornstarch has cooked completely - the curd will still be relatively thin when finished. Remove from the heat and strain the curd through a fine-meshed sieve set over a heatproof bowl. Cover the bowl with plastic wrap and transfer to the refrigerator to cool completely. It will thicken slightly as it cools.
Prepare and Bake Meringue: Place the egg whites in the bowl (clean and free of any grease) of a stand mixer fitted with a whisk attachment. Whisk over low speed for 1 to 2 minutes, or until the egg whites are foamy and frothy. Increase speed to high and continue whipping for an additional 1 to 2 minutes. With the mixer on high speed, slowly sprinkle and add the granulated sugar, one tablespoon at a time, whisking until the meringue reaches a stiff peak.
Add the vanilla bean paste (or extract), cornstarch, and vinegar, and whisk at high speed to combine. Scrape the bottom of a bowl with a spatula to ensure that all the ingredients are incorporated evenly. Transfer the meringue to the center of parchment paper lined sheet pan. Using a small offset spatula, smooth the meringue into a round using the traced circle as a guide. Then use the offset spatula to build up the sides of the meringue slightly, this will help create slight edges to contain the whipped cream, curd, and fresh raspberries for assembly.
Bake for roughly 1 hour. Turn off the heat and use a wooden spoon to prop open the oven door slightly, allowing the meringue to completely cool in the oven (roughly 1 hour). It will be crisp and slightly cracked on the outside, but slightly soft on the inside.
Prepare Whipped Cream: Combine the cold heavy cream and vanilla bean paste (or extract) in the clean bowl of a stand mixer, fitted with a whisk attachment (or alternatively, use a hand-held mixer). Beat the cream until it reaches soft peaks. Do not over beat. Note: Since the dessert is plenty sweet enough, I prefer to leave out any additional sugar from the whipped cream.
Assembly: Dollop the top of the baked and cooled meringue with the whipped cream and spread rustically into an even layer. Top the cream with the chilled raspberry curd and garnish with fresh raspberries. Sift confectioners’ sugar on top of the fresh raspberries. Use a spoon to scoop servings.
Storage Tips:
Leftover pavlova can be wrapped well and stored overnight in the refrigerator; however, the meringue will gain moisture and lose crispness with time.