Grease and flour a 9"x5" loaf pan and set aside.
Preheat oven to 350 degrees.
Place the chocolate chips and walnuts in a small bowl and toss with 2 tablespoons of the gluten free flour.
In a medium mixing bowl, whisk together the remaining gluten free flour, baking soda, and salt.
Stir together the mashed bananas, oil, sugar, egg and sour cream in a large mixing bowl.
Add the flour mixture to the banana mixture and stir until combined.
Fold in the chocolate chips and walnuts.
Spread the batter in the loaf pan and bake for about 60 minutes or until a wooden pick inserted in the center comes out clean.
Cool the pan on a wire rack for about 15 minutes. Remove the bread from the pan and allow to cool completely on the rack.
Recipe slightly adapted from Brown Eyed Baker