First, peel and mash the ripe bananas in a small bowl. Set aside until you need them.
In a large mixing bowl, stir together the dry ingredients: flour, baking soda and salt. Then stir in the walnuts.
In a medium size mixing bowl, stir together the wet ingredients: oil, brown sugar, eggs, sour cream and vanilla extract.
Now stir the wet ingredients into the dry.
Last, stir in the mashed bananas.
Spray a bread loaf pan with nonstick cooking spray, or you can grease with softened butter or line with parchment paper.
Spoon the batter into the prepared loaf pan and top with turbinado sugar if using.
Bake in the oven at 350°F for 45-50 minutes. A toothpick inserted into the center should come out mostly clean (no completely raw batter clinging to it).
Allow the bread to cool in the pan before removing. Once room temperature, you can slice and serve.