Cream the butter and cream cheese. Add the sugar and then the egg yolk. Add the lemon rind and mix well. Mix the salt with flour and add in small amounts to the butter-sugar mixture, blending well after each addition. Add the walnuts and refrigerate the dough for 2 hours.
When the dough is ready to bake, form it into three logs, each approximately 6 inches long, and flatten the logs slightly. Cut 12 1-by-3-inch ovals from each log.
Bake the cookies on a lightly greased cookie sheet at 325 for 18 to 22 minutes, until they are lightly browned.
Cool the cookies on racks and glaze with a mixture of the confectioners' sugar and lemon juice.