Add the aquafaba, vanilla, and cream of tartar to a large bowl or the bowl of a mixer. Use the mixer or a hand mixer to beat the liquid for about 1 minute until it starts to get fluffy. Very slowly sprinkle in the sugar a spoonful at a time while the mixer is on. Continue to beat for about 10 minutes until a stiff peak is formed. When you lift the beater the fluff should look glossy and hold a stiff peak, even if you jiggle the bowl the peak should stay as is. It may take more or less time depending on your mixer and brand of aquafaba.
*I prefer using canned chickpeas that are salt-free (check the ingredients). The chickpeas with salt may have a slight bean taste, whereas the salt-free ones do not. Either salted or unsalted will still work. 1 can of chickpeas will contain about 1 cup of liquid.*Store leftovers in an air-tight container in the fridge. It may start to decrease in fluffiness after a day, but you can give it a little whisk to liven it back up again.