Preheat oven to 350F.
Grease 9X5 loaf pan.
Combine baking soda and sour cream.
Cream butter and sugar in large bowl. When light in color, add salt.
Add eggs, one at a time.
Add bananas and sour cream mixture.
Stir in the flour and baking powder, working as little as possible.
Fold in the nuts and chocolate.
Turn into loaf pan, and bake till cake tester comes out clean, about 45 minutes to an hour depending on the size of the pan.
Remove from pan, and allow to cool on rack.