Prepare the Sugar: Pulse the caster sugar in a blender until fine, being careful not to over-blend into powdered sugar.
Preheat the Oven: Set your oven to 200°F (93°C).
Prepare the Baking Sheet: Line a large baking sheet with parchment paper and set aside.
Beat the Egg Whites: In a stand mixer fitted with the whisk attachment, beat the egg whites on medium speed until soft peaks form.
Gradually Add Sugar: Gradually add the caster sugar, one tablespoon at a time, mixing well between each addition.
Add Stabilizers: Add the vinegar, cornstarch, salt, and vanilla. Continue whipping until stiff, glossy peaks form.
Shape the Meringue: Spoon the mixture onto the prepared baking sheet into 9 rounds, each about 4 inches wide.
Bake: Place in the oven and bake for 1 hour and 15 minutes. Do not open the oven door during baking or while cooling.
Cool Completely: Turn off the oven and allow the meringues to cool completely inside, ideally 3–4 hours.
Prepare the Lemon Curd: While the meringues are cooling, make the lemon curd if you haven’t already.
Assemble: Once the meringues are fully cooled, top each with a dollop of lemon curd, followed by your choice of fruit and toppings.
Serve and Enjoy!