Cream butter and sugar until light and smooth. Add egg; beat until fluffy. Stir in sour cream and vanilla. Sift together flour, salt, baking soda, and baking powder. Stir sifted dry ingredients into creamed mixture. Chill for 1 to 2 hours. Place small balls of dough onto greased baking sheet. Grease bottom of a glass then dip in sugar or cinnamon sugar. Press each ball of cookie dough into a thin circle with sugared bottom of glass. Press a pecan half into the top of each cookie. Bake at 350° for 8 to 10 minutes, or until lightly browned. Remove to racks to cool.
Makes about 5 dozen cookies.