In a large bowl, cream butter and confectioners' sugar until light and fluffy. Beat in the egg yolk, preserves, orange peel and vanilla. Combine flour and salt; gradually add to creamed mixture and mix well. Cover and refrigerate for 2 hours or until easy to handle.
Roll dough into 1-in. balls. In a shallow bowl, beat egg white until foamy. Place pecans in another shallow bowl. Dip each ball into egg white, then into pecans.
Place 2 in. apart on ungreased baking sheets. Bake at 350° for 10-12 minutes or until lightly browned. While still warm, press a cherry half into the center of each cookie. Remove to wire racks to cool. Yield: 3 dozen.