Preheat oven to 325°F.
Grease 10-inch tube pan.
Finely grate colored portion of orange peel.
Measure 2 teaspoons orange peel; set aside.
Beat butter in large bowl with electric mixer at medium speed until creamy, scraping down side of bowl once.
Gradually add sugar, beating until light and fluffy.
Beat in vanilla and orange peel.
Add eggs, 1 at a time, beating 1 minute after each addition.
Combine flour, salt and baking soda in small bowl.
Add to butter mixture alternately with sour cream, beginning and ending with flour mixture.
Beat well after each addition.
Pour into prepared pan.
Bake 1 hour and 15 minutes or until cake tester or wooden skewer inserted in center comes out clean.Meanwhile, prepare Citrus Topping.
Spoon over hot cake; cool in pan 15 minutes.
Remove from pan to wire rack; cool completely.