Grease or line a loaf pan with parchment paper.
Pre-heat oven to 350°F with rack in the middle of the oven.
Add cider vinegar to plant-based milk (soy), stir to combine and thicken and let rest while preparing the dry ingredients.
Combine all dry ingredients in a large mixing bowl.
Combine mashed banana and maple syrup with the soy milk mixture.
Stir wet ingredients ingredients into dry ingredients until combined ONLY once oven has pre-heated. If using organic baking powder, it is typically only single-acting (activated by moisture) rather than double-acting (also activated by heat). You will want to place the loaf pan in the oven as soon as you have mixed the wet and dry ingredients to avoid the bubbles escaping before the loaf has started to bake!
Add the mixed batter to the loaf pan and top with sliced banana if doing so, before placing in the oven to bake straight away.
Bake for 55 to 60 minutes or until an inserted skewer or toothpick is removed cleanly. Add an additional 5 minutes, as required. We baked ours for 55 minutes, but how hot your oven is and your particular flours can always influence baking time requirements.
Let banana bread cool completely before slicing.