Preheat oven to 350°F. Line cookie sheets with Silpat or parchment paper; set to side.
Cream sugar and butter in mixer
Add egg, vanilla and peppermint flavoring to bowl; beat at medium speed, scraping bowl often, until creamy.
Add flour, cream of tartar, baking soda and salt; beat at low speed until well mixed.
Hand stir in peppermint candy.
Shape dough into 3/4-inch balls; roll in sugar mixture. Place 2 inches apart onto your prepared cookie sheets.
Bake 8-10 minutes or until edges are lightly browned. Do not over bake. Cool 3 minutes on cookie sheet; remove to cooling rack. Cool completely before icing.