01 - Preheat oven to 200°F. Line two baking sheets with parchment paper.
02 - In a clean, grease-free mixing bowl, combine egg whites and cream of tartar. Beat with an electric mixer on medium speed until soft peaks form.
03 - Gradually add sugar, about one tablespoon at a time, and continue beating on high speed until the meringue reaches stiff, glossy peaks, approximately 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 clean food-safe brush, paint three stripes inside the bag: one with red gel food coloring, one with blue, and leave one section plain for white.
06 - Gently spoon the meringue mixture into the prepared piping bag, keeping the painted stripes intact.
07 - Pipe small mound-shaped kisses, approximately 1 to 1.5 inches wide, onto the prepared baking sheets, spacing each about 1 inch apart.
08 - Bake for 1 hour and 15 minutes until the kisses are dry and crisp. Turn the oven off and allow meringues to cool inside with the door closed for 1 hour to further dry.
09 - Carefully peel meringues from the parchment and store in an airtight container at room temperature for up to 5 days.