Make the Meringues:

1. Preheat the oven to 200°F (95°C). Line two baking sheets with parchment paper.
2. In a stand mixer (or using a hand mixer), beat egg whites, salt, and cornstarch until foamy. Gradually add sugar while beating. Continue to beat for 2–3 minutes on high until stiff peaks form.
3. Mix in vinegar and vanilla extract, beating until combined.
4. Spoon meringue onto the baking sheets, shaping small nests with the back of a spoon.
5. Bake for 2 hours until dry and crisp. Turn off the oven and let the meringues cool completely inside.

Make the Citrus Curd:

1. In a small saucepan over medium heat, simmer citrus juice until reduced by half (about 3–5 minutes). Let cool slightly.
2. In a stand mixer, beat butter and sugar until light and fluffy (about 2 minutes).
3. Add egg yolks and whole eggs one at a time, mixing well. Stir in salt, citrus juice, and ginger.
4. In a double boiler, heat the mixture over simmering water, stirring constantly for about 10 minutes until thickened (166°F on a thermometer).
5. Strain through a sieve into a bowl to ensure a smooth consistency. Let cool, then store in an airtight container in the fridge for up to a week.

Assemble the Meringues:

1. Spoon citrus curd into the center of each meringue.
2. Top with fresh berries, a sprig of mint, and a dusting of powdered sugar.
3. Serve immediately and enjoy!