preheat oven @ 350 degrees F. lightly grease a 9x5 loaf pan with coconut oil.
mash bananas at bottom of large bowl. whisk in coconut oil, then your starter, honey, egg, and vanilla extract.
sift flour and cocoa powder (good-bye lumpy cocoa powder, hullo silky smooth luxury) over wet ingredients, and add the baking soda and salt. stir dry and wet ingredients with spatula or spoon until just combined.
lightly fold in chocolate, walnuts, and any other add-ins you'd like to include.
pour into pre-greased pan and bake 50-60 min @ 350 degrees F, until tester or toothpick inserted into center comes out batter free. cool in pan for 15 min, and then run a knife around the edge. carefully invert onto cooling rack and onto serving platter.
serve warm (recommended!) or at room temperature. keeps for 4 days room temp, and longer in the fridge wrapped in foil or in an air tight container.