01 - Preheat oven to 200°F. Line two baking sheets with parchment paper.
02 - In a thoroughly clean, grease-free mixing bowl, combine egg whites and cream of tartar. Using an electric mixer, beat on medium speed until soft peaks form.
03 - Add granulated sugar to the mixture about one tablespoon at a time, beating on high speed after each addition. Continue until the meringue forms stiff, glossy peaks, approximately 5 to 7 minutes.
04 - Gently beat in salt and vanilla extract until the mixture is just combined.
05 - Fit a piping bag with a large star or round tip. Using a food-safe brush, paint a stripe of red gel food coloring and a stripe of blue gel food coloring along opposite sides inside the piping bag, leaving the center for the white meringue.
06 - Carefully spoon the meringue mixture into the prepared piping bag, taking care to keep the color stripes distinct.
07 - Pipe small, kiss-shaped mounds about 1 to 1.5 inches wide onto the prepared baking sheets, spacing each mound approximately 1 inch apart.
08 - Bake meringues for 1 hour and 15 minutes or until dry and crisp. Turn off the oven and allow meringues to cool inside with the oven door closed for an additional hour to ensure extra crispness.
09 - Carefully peel meringue kisses from parchment paper and store in an airtight container at room temperature for up to five days.