Add the sugar, oil, eggs, vanilla, and banana to a mixing bowl and whisk together until the sugar has dissolved and the mixture is smooth and creamy.
Add the sourdough discard and stir until fully incorporated.
In a separate bowl, mix the flour with the salt, baking soda, baking powder, and cinnamon. Add the dry ingredients to the wet and fold them together until fully incorporated. Set the batter aside to rest for 10 minutes.
Preheat the oven to 350°f.
Add muffing liners to your muffin tin.
Fill each muffin liner 3/4 full and evenly among the liners.
Bake the muffins at 350°f for 25 minutes or until the muffins are golden brown and fully cooked, use a toothpick to test the center muffin.
Remove the cooked muffins, and set them on a cooling rack until cool to the touch.
Enjoy muffins with a little butter!