01 - 
                Set the oven to 350°F. Coat a 9x5 loaf pan in non-stick spray.
              
              
              
                02 - 
                In a medium bowl, toss together the flour, salt, and baking soda with a fork, then put it aside.
              
              
              
                03 - 
                In a large mixing bowl, beat the butter and both sugars on medium-high with a mixer for 1-2 minutes until smooth.
              
              
              
                04 - 
                Mix in the eggs, vanilla, and bananas. Scrape the bowl’s edges if needed. Some banana lumps are okay.
              
              
              
                05 - 
                Carefully fold in the dry mix and the sourdough starter by hand until just combined.
              
              
              
                06 - 
                Pour the batter into the loaf pan and bake for 55-65 minutes. Check if it’s done by inserting a toothpick—it should have some crumbs but no batter. Let it cool for 10 minutes before slicing.