Place egg whites in a small bowl; let stand at room temperature 30 minutes., Preheat oven to 250°. Add vanilla, cream of tartar and salt to egg whites; beat on medium speed until foamy. Gradually add sugar, 1 tablespoon at a time, beating on high after each addition until sugar is dissolved. Continue beating until stiff glossy peaks form, about 7 minutes., Cut a small hole in the tip of a pastry bag or in a corner of a food-safe plastic bag; insert a #32 star tip. Transfer meringue to bag. Pipe 1-1/4-in.-diameter cookies 2 in. apart onto parchment-lined baking sheets., Bake until firm to the touch, 40-45 minutes. Turn off oven; leave meringues in oven 1 hour (leave oven door closed). Remove from oven; cool completely on baking sheets. Remove meringues from paper; store in an airtight container at room temperature.