In a large bowl, cream shortening and sugar until light and fluffy, 5-7 minutes. Beat in the egg, sour cream and vanilla. Combine the flour, baking soda, baking powder and salt; add to the creamed mixture and mix well. Chill for at least 1 hour. , Drop by tablespoonfuls 2 in. apart onto greased baking sheets. Bake at 425° for 7-8 minutes or until lightly browned. Remove to wire racks to cool. , For frosting, melt butter in a saucepan until golden brown; stir in confectioners' sugar, vanilla and enough water to reach a spreading consistency. Frost cooled cookies.