Combine flour, soda and salt. In another bowl, cream butter and 1 cup sugar until fluffy. Add eggs and vanilla; mix well. Blend in flour mix, alternating with sour cream. In another bowl, mix together apples, cinnamon, 1/2 cup sugar and nuts. Spread half the batter in a greased 9-inch tube or Bundt pan. Sprinkle half the cinnamon-apple mix over the batter. Spoon in the rest of the batter and sprinkle on the rest of the cinnamon-apple mix. Bake at 375° for 40 to 50 minutes. Cool 10 minutes before removing from pan.