01 - Preheat oven to 200°F. Line two baking sheets with parchment paper.
02 - In a grease-free mixing bowl, combine egg whites and cream of tartar. Using an electric mixer, beat on medium speed until soft peaks form.
03 - Gradually add granulated sugar, a tablespoon at a time, beating on high speed until stiff, glossy peaks form, about 5 to 7 minutes.
04 - Beat in salt and vanilla extract until just combined.
05 - Fit a piping bag with a large star or round tip. Using a food-safe brush, paint one red and one blue stripe inside the bag, leaving a white space.
06 - Carefully spoon the meringue into the piping bag to retain the color stripes.
07 - Pipe small kiss-shaped mounds, about 1 to 1.5 inches in diameter, onto prepared sheets, spacing each about 1 inch apart.
08 - Bake for 1 hour 15 minutes until dry and crisp. Turn off the oven and let meringues cool inside with the door closed for 1 hour to maximize crispness.
09 - Gently peel meringues off the parchment and store in an airtight container at room temperature for up to 5 days.