Cream the butter and cream cheese. Add the sugar and then the egg yolk. Add the lemon rind and mis well. Mix the salt with the 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 x 3 inch ovals from each log. Bake the cookies on a lightly greased cookie sheet at 325 for 18-22 minutes, until they are lightly browned. Cool the cookies on racks and glaze with a mixture of the confectionars sugar and lemon. Note: this recipe can be doubled for holiday times