Move the racks in your oven to the lowest setting.
Preheat the oven to 200°F
On a piece of parchment that fits your cookie sheet, trace a 8 inch circle. Use a 8 inch cake pan as a template.
Flip the parchment over, place on cookie sheet, and set aside.
Add six egg whites to the bowl of a stand mixer.
Using the whisk attachment, whip the egg whites until opaque, and light and fluffy, the soft peak stage.
While the mixer is running, gradually add the sugar. Whatever you do, do not add all the sugar at once. Add it in at least five batches.
Continue whipping the whites until they are glossy and achieve stiff peaks.
In a small bowl, add the white wine vinegar, cornstarch, vanilla, and salt.
Mix well to combine.
Once the egg whites and sugar are at stiff peak stage, add the white wine vinegar mixture.
Whip until well incorporated.
Dip a finger into the egg white mixture.
Use the egg whites on your finger to tack down the underside of the parchment paper to the cookie sheet. Do this by making a small dot of meringue in each corner.
Place the rest of the meringue in the center of the traced circle.
Use a spatula to move the meringue to the edge of the tracing.
You should have a low flat cylinder of meringue.
Make a divot in the center of the meringue. It will look like a very shallow volcano.
Feel free to use the spatula to create a decorative edge around the meringue. Do this by making lines in the meringue using the tip of the spatula. I like to move from the bottom to the top at an angle.
Place the meringue in the oven, and bake for 1 hour and 30 minutes.
Turn off the oven, and crack the oven door.
Leave the meringue in the oven for another hour to allow it to continue to dry out.