Preheat oven to 350F (180 C)
In a large bowl, mash your bananas with a potato masher or a fork until you have as little chunks as possible.
Stir in sourdough discard, vegetable oil, and brown sugar and mix well to incorporate.
Sift in flour, baking powder, and baking soda, and a pinch of salt. Mix until just incorporated (try not to overmix, it'll be gummy otherwise). It should have the texture of a light and fluffy cake batter.
Grease a loaf pan with either oil or vegan butter. Pour batter into the greased pan, then bake for 60 minutes (or until a cake tester comes out clean). I usually can tell its ready once the sides start to pull away from the pan.
Cool for about 10 minutes in the pan, then transfer onto a wire rack to cool (set it right side up or you'll get weird grid marks on top haha).
