In a large bowl, cream butter and 1/2 cup sugar until light and fluffy. Beat in egg and vanilla. Combine flour and salt; gradually add to creamed mixture and mix well. Cover and refrigerate for 15 minutes.
On a floured surface, roll out dough to 1/4-in. thickness. Cut with a floured 2-in. cookie cutter or shape into 2-in. x 1-in. rectangles. Place 2 inches apart on ungreased baking sheets. Combine orange peel and remaining sugar; sprinkle over cookies.
Bake at 350° for 14-16 minutes or until the edges just begin to brown. Remove to wire racks to cool. Melt chocolate chips; decorate cookies.