Preheat oven to 175° F (80° C). Line a baking sheet with parchment paper and set aside.
Use the vinegar to wipe the inside of a stainless steel mixer bowl, as well as the whip attachment and a whisk. Pour a little water (I usually pour enough to fill about five centimeters deep) into a medium pot and place over medium heat.
Place the egg whites and sugar in the mixer bowl and whisk together to combine. Place the bowl over the pot of simmering water (but not touching the water) and whisk constantly, until the mixture thins and is completely smooth. I usually dip a clean spoon into the mixture and then rub it between my fingers to test whether it’s ready. When you can no longer feel any granules of sugar, you can remove the bowl from the heat.
Place the bowl on a stand mixer fitted with the whip attachment, add the salt and cream of tartar and beat on medium-high speed, until meringue triples in volume and becomes thick and glossy. Add the vanilla extract and beat to combine. Add the food colouring and beat until well-blended.
Fit a pastry bag with a large piping tip and pipe circles onto the parchment paper, spacing apart slightly (meringues don’t spread, so they can be fairly close together).
Once all of the meringues have been piped, top with sprinkles. Transfer the baking sheet to the oven and bake for about two hours or until meringues lift easily off of the parchment paper. Allow the meringues to cool completely on the baking sheets.
Meringues will keep for up to two weeks when stored in an air-tight container.
Greasy residue (from butter, oils, etc.) and egg whites are not friends when making meringues! Fats can prevent your meringue from whipping up into billowy goodness and leave you instead with a soupy, egg mixture. To prevent this, be sure to wipe all bowls and utensils with vinegar, which will get rid of any oily residue.
If you’re having trouble with the parchment paper sliding around while you’re piping the meringues, apply a little bit of meringue to the underside of the corners of the parchment paper. Press into the baking sheet and you’re in business!