Heat oven to 200°F. Grease 2 large cookie sheets with shortening or cooking spray. In small bowl, beat egg whites, cream of tartar and salt with electric mixer on medium speed until foamy. On high speed, add sugar, 1 tablespoon at a time, beating until sugar is dissolved, meringue is glossy and very stiff peaks form. Beat in mint extract. With rubber spatula, fold in food color, 1 drop at a time, until well blended and desired color.
Use disposable decorating bag or gallon-size food storage plastic bag with 1/2-inch hole cut in one bottom corner of bag (if desired, fit large star tip in decorating bag or in hole of plastic bag). Spoon meringue into bag; twist top of bag to seal. Squeeze bag to pipe meringue into 1-inch puffs onto cookie sheets. Sprinkle each with candy sprinkles.
Bake on middle oven rack 2 hours. Immediately remove cookies from cookie sheets; place on wire racks. Cool completely, about 5 minutes.