Preheat your oven to 210°F (100°C). Line 3 baking sheets with parchment paper.
In a clean, dry bowl of a stand mixer fitted with a whisk attachment, add the aquafaba and cream of tartar. Begin whipping the aquafaba on medium speed until it forms soft peaks.
Gradually add the sugar, a spoonful at a time, while continuing to whip the aquafaba. Increase the speed to high and continue whipping. This should take about 8-10 minutes. Whip until you reach stiff peaks, and the meringue is glossy and holds its shape when you lift the beaters. Add vanilla extract into the meringue and beat until just mixed.
Transfer meringue mixture into pastry piping bag fitted with desired tip and pipe small meringues on prepared baking sheets.
Bake in the preheated oven for about 1 hour and 30 minutes (periodically changing position of the trays for even cooking), or until the meringues are crisp on the outside. It's important to bake them at a low temperature to avoid browning.
Once they are done baking, turn off the oven and leave the meringues in the oven for another hour or until they cool completely. This helps to further dry them out.
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Notes
To store: Vegan meringues are best stored in an airtight container at room temperature. They will stay fresh for 2 to 3 days.To freeze: Freeze in an airtight container for up to 2 months and thaw them at room temperature. They may lose some of their crisp texture after thawing, but they will still taste delicious.