Preheat oven to 350˚F. In a mixing bowl, cream butter (margarine) with an electric mixer. Add granulated sugar and salt and beat well. Add pecans or walnuts and flour and work dough until all ingredients are thoroughly mixed. Roll dough into a ball, cover with plastic wrap and refrigerate 1½ hours or until dough is firm. (Dough can be made several days ahead.)

Allow dough to come to room temperature. Form into balls slightly smaller than walnuts. If dough is too dry or stiff, squeeze it with your hand before forming the balls. Put balls on a baking sheet and bake 18 minutes. Gently remove to a rack to cool. When cool, roll in confectioners’ sugar. Store in an airtight container. 

Note: These cookies are also know as Russian teacakes and Mexican wedding cakes.