Preheat the oven to 200°F (95°C). Line 2 baking sheets with parchment paper, or silicone mat.
In a large mixing bowl with whisk attachment, whisk egg whites on medium speed until frothy.
Add cream of tartar and salt. And continue to whip the meringue until it turn white.
Start adding sugar one tablespoon at a time, while mixer is still running. Allow the sugar to dissolve after each addition.
Increase the speed to medium high, once all the sugar is added.
When the meringue reaches soft peaks (it's when you lift the whisk, merigue tip droops into a hook), add vanilla extract and food coloring, if desired.
Continue to beat the meringue until stiff peaks form. When you lift the whisk, you'll see the meringue tip stands straight up.
Transfer the meringue into a pastry bag, fitted with decorative tip, and pipe into desired shapes and size on lined cookie sheet.
Bake for 40-90 minutes, depending on size of the cookies. Meringues are done when they are hard to the touch, can be easily lifted and crisp all throughout. Turn off the oven, and let the cookies slowly cool in the oven.