In a large bowl, cream butter and sugars until light and fluffy. Beat in egg, lime juice and zest. Combine flour and cornmeal; gradually add to creamed mixture and mix well.
Shape into two 12-in. rolls; wrap each in plastic. Refrigerate 30 minutes. Shape each roll into a square-shaped log. Freeze 1 hour or until firm.
Preheat oven to 350°. Unwrap logs and cut into 3/8-in. slices. Place 1 in. apart on parchment paper-lined baking sheets. Bake 11-14 minutes or until set. Remove to wire racks to cool completely.
Combine confectioners' sugar and lime juice; spread over cookies. Decorate with sprinkles. Let stand until set.