In a large mixing bowl stir together softened cream cheese and peppermint extract. Gradually add powdered sugar, stirring until mixture is smooth. (Knead in the last of the powdered sugar with your hands.) Add black icing; knead until food coloring is evenly distributed.
Form cream cheese mixture into 3/4-inch balls. Roll each ball in sanding sugar if desired; place on waxed paper. Cover mints with paper towels; let dry overnight. Store in a tightly covered container in the refrigerator or freeze up to 1 month. Makes 96 to 120 pieces.