Preheat oven to 300 degrees Fahrenheit. Line two rimmed baking sheets with Gefen Parchment Paper.

Place egg whites in a bowl and whisk with an electric mixer on medium speed for five minutes, and then increase speed to high, beating until stiff peaks form (you can test this stage by turning the whisk upside down, and the peaks of the thick meringue should hold, pointing straight up, or just collapsing at the very tips).

Gradually, add sugar one tablespoon at a time, waiting 30 seconds in between additions.

Once all the sugar is added, whisk for six more minutes, until the meringue is glossy and stiff.

Scrape the sides of the bowl with a spatula and add the salt, and vinegar or lemon juice at once (and vanilla, if using), and whisk for two more minutes.

Place meringue on prepared sheets by using a spatula, piping bag or spoons, depending on the desired shape and size.

Lower down the oven temperature to 250 degrees Fahrenheit and bake meringues for an hour to an hour and a half (time will depend on size). Turn oven off, but let meringues cool completely inside the oven (this will help with the drying process), you could leave them in the turned off oven overnight.

Serve or use prepared meringues in a composed dessert.