Preheat the oven and prepare the baking sheets

• Preheat the oven to 200°F (95°C).
• Line two baking sheets with parchment paper.

Make the meringue

• Beat the egg whites with the salt and cornstarch.
• When the egg whites are foamy, pour in the sugar.
• Beat for an additional 3 minutes on high, until stiff peaks form.
• Pour in the vinegar and vanilla extract and beat again.

Shape the pavlovas

• Spoon out big dollops of meringue onto the baking sheets.
• Using the back of a spoon, create cavities in each dollop.
• Repeat until all of the meringue is used (about 12 pavlovas).

Bake the meringues

• Bake for 2 hours, or until the meringues are dry and crisp.
• Turn off the heat and allow the meringues to come to room temperature.

Reduce the lemon juice

• To a saucepan placed over medium heat, simmer the lemon juice until it reduces by half (to about 1/3 cup).

Start the curd mixture

• In a heatproof bowl that fits into a saucepan, add the butter and sugar and beat together.
• Add the egg yolks and the eggs, beating until combined.
• Stir in the salt and add the reduced lemon juice. The mixture will look curdled — that's normal!

Cook the curd over a water bath

• Rinse out the small saucepan used earlier and fill it with a few inches of water.
• Bring the water to a simmer and place the stainless steel bowl of curd mixture on top.
• Stir constantly, heating the curd slowly enough that the sugar has time to dissolve and the mixture becomes cohesive.
• The curd will thicken as it cools.

Strain and chill the curd

• Pour the curd through a sieve into a chilled bowl.
• Transfer the curd to a container and keep it in the fridge.

Assemble and serve

• Add the lemon curd to each of the pavlovas.
• Top with fruit of choice and a little sprig of mint.
• Dust with powdered sugar and enjoy.