Heat oven to 225° F. Line 2 baking sheets with parchment.
Beat the egg whites and vanilla with an electric mixer on medium in a large bowl until foamy, about 1 minute. Add the cream of tartar and salt and beat until soft peaks form, about 1 minute more. Slowly add the sugar; increase speed to medium-high and continue to beat until the meringue is glossy and stiff peaks form, 4 to 6 minutes more. Fold in 2 tablespoons of the crushed red hots.
Drop or pipe small mounds (about 1½ tablespoons each) onto the prepared baking sheets and sprinkle with the remaining red hots.
Bake until firm and dry, 1 to 1½ hours (1 hour is great if you like a meringue with a slighly soft center). Turn the oven off and cool the meringues in the oven, 1½ to 2 hours.
Storage suggestion:Keep cookies at room temperature in an airtight container for up to 3 days.