1. Heat oven to 450°F.
2. Sift flour, baking powder, baking soda and salt together into a bowl. Blend in sour cream. Stir in milk to make a soft dough.
3. Put a small amount of flour on a board or counter top. Turn dough out of bowl. Knead gently for a few minutes.
4. Roll or pat out dough to 1/2 inch thick. Cut out biscuits with a lightly floured biscuit cutter.
5. Place biscuits on a very lightly buttered baking sheet. Bake 10 minutes or until lightly browned on top.