In a large bowl, cream shortening and sugar until light and fluffy. Beat in extract. Stir in sour cream and peel.
Combine the flour, baking soda and salt; gradually add to creamed mixture and mix well.
Divide dough into three balls; cover and refrigerate for 3 hours or until easy to handle.
On a lightly floured surface, roll out dough to 1/4 inch thickness. Cut with a floured star cookie cutter. Place 1 in. apart on ungreased baking sheets.
Bake at 375Â° for 6-8 minutes or until edges are lightly browned. Remove to wire racks to cool.
For frosting, in a small bowl, combine the confectionersâ€™ sugar, margarine, extract, food coloring if desired and enough milk to achieve spreading consistency.
Frost cookies; sprinkle with colored sugar if desired.