Preheat the oven to 100ÂșC and line a baking sheet with baking paper.
In a medium mixing bowl, swill the vinegar around the whole bowl, and discard (there should only be trace amounts left).
Add the aquafaba and vanilla (if using), and use an electric egg beater to mix on low speed, gradually increasing the speed.
Beat for 5 to 10 minutes, until stiff peaks form.
Continuing to beat, slowly add the sugar a tablespoon at a time.
Beat until silky in texture, with no grainy texture â now it's ready.
With a teaspoon, spoon dollops of the mixture onto the baking paper, leaving a little space between them.
Bake at 200ÂșC for 1 Âœ hours, then turn off the oven and leave the meringues in the oven until cool.
Check for doneness by cracking one open: if it's dry inside, it's ready.
Store in an airtight container (if you don't, they'll turn into a sticky mess).