Preheat oven to 400°. In a large bowl, combine the flour, sugar, baking powder, baking soda and salt; add fresh or frozen berries and toss gently. Combine the eggs, sour cream, oil and vanilla; mix well. Stir into dry ingredients just until moistened.
Fill greased muffin cups two-thirds full. Bake at 400° for 20-25 minutes or until a toothpick inserted in the center comes out clean. Cool for 5 minutes before removing from pans to a wire rack. Serve warm.
Editor's Note: If using frozen berries, do not thaw before adding to batter.