1. Preheat oven to 350 degrees F. Grease/spray a 9" square baking pan; set aside. Put one teaspoon vinegar in a liquid measuring cup and add enough soy milk to equal 1/4 cup; mix together and set aside.
2. Meanwhile, in a separate bowl, mix dry ingredients together; set aside. In another bowl, beat oil, vanilla, and bananas. Gradually add in dry ingredients as well as the milk mixture. Beat until smooth.
3. Pour batter into prepared pan. Bake for 25-30 minutes until brown on top and toothpick inserted near center comes out clean. Serve warm, if desired.
Notes: You can add nuts or desired spices (like cinnamon). This can also be made in a standard size loaf pan (adjust cooking time accordingly).