Preheat oven to 350°.
Coat a 12-cup Bundt pan with cooking spray; set aside.
Sift together flour, cornstarch, and salt twice; set aside. Combine dried fruits with 1/4 cup flour mixture, tossing to coat.
Combine sugar and next 4 ingredients (sugar through vanilla) in a large bowl, and beat at medium speed of mixer until well-blended (about 5 minutes). Add eggs and egg whites, one at a time, beating well after each addition. Combine sour cream and baking soda; stir well. Add flour mixture to sugar mixture alternately with sour cream mixture, beginning and ending with flour mixture. Mix well after each addition. Gently fold in dried fruit mixture.
Pour batter into prepared pan. Bake at 350° for 1 hour or until wooden pick inserted in center comes out clean. Cool in pan 10 minutes on a wire rack; remove from pan. Let cool completely on wire rack. Dust with powdered sugar.