Preheat oven to 250 degrees F. Trace a piece of paper to the shape of a circle. Put in on a baking sheet and line it with parchment paper.
In a stand mixer bowl and using the wire whip, beat the egg whites and salt until it becomes foamy. Add cream of tartar and beat until soft peak form.
While the mixer is in low speed, add the superfine sugar 1 tablespoon at a time until it’s all mixed in. Keep mixing until the egg whites becomes a stiff peak form.
Add the vanilla extract and blue and green food coloring and mix evenly. Use a spatula to scrape the sides to make sure all the colors are mixed in.
Pour in a pastry bag with a flower piping tip and pipe it around the circle.
Bake for about 1 hour. Shut off the oven. Leave the meringues in the oven to dry out. After it’s cooled, store in an airtight container.