Preheat the oven to 200F (100C). Line a baking sheet with parchment paper.
Add the aquafaba to a mixer bowl along with the vanilla extract and the cream of tartar. Start beating on high, and very slowly as it whips, add in the the sugar one spoonful at a time. You may need to stop and scrape off any sugar that stuck to the sides of the bowl. Continue to beat, stopping every now and then to check the meringue. When stiff peaks hold in the meringue without it collapsing, they are ready. It took me about 6 to 6 1/2 minutes to reach the stiff peaks.
Use a pastry bag, or a spoon to dollop on the meringue into even mounds onto the prepared baking sheet.
Bake for 1 1/2 to 2 1/4 hours, rotating the pans half way through. Now it's a little difficult to tell exactly when they are done, and I really racked my brain on how to share this information, but there is not much of a visual cue, so you are going to have to go with your gut a little on this one. If the meringues are small or you want a chewy center, opt for less time. If they are large or you prefer a meringue that is crunchy all the way through, opt for more time. It's not very easy to tell when they are ready just by look, so the best way is if you are able to take one out of the oven, (carefully tear a piece of parchment off with a meringue on it) let it cool, and see if it's the correct texture. If it is, take the rest out of the oven. If not, bake longer. When they are ready let them cook and enjoy!
Sam Turnbull https://itdoesnttastelikechicken.com/vegan-meringue-cookies/