Preheat the oven to 350 degrees Fahrenheit. Grease a loaf pan and set aside.
In medium-large bowl, whisk together the flour, brown sugar, baking soda, and sea salt.
In a large glass measuring cup mash the bananas. You should have close to 1 ½ cups of mashed banana. Add more banana or applesauce until you get exactly 1 ½ cups. Add ½ cup oil, eggs, yogurt, and vanilla until everything is a smooth liquid.
Pour the banana mixture into the flour mix. Add the chopped nuts and chocolate chips if using. With a spatula, stir everything together in big, gentle folds only until everything is combined and no flour pockets remain. There may be a few flour streaks left (this is okay, as you do not want to over-mix the batter; the loaf will not rise as much or be as fluffy).
Fill the loaf pan with the banana batter, spreading it to make it even. Bake at 350 F for 40-50 minutes. The loaf is done when a toothpick is inserted and comes out clean (not with wet batter on the toothpick) and when the loaf springs back to a light touch.
Let the loaf cool in the tray for 5 minutes before removing it from the pan and placing it on a cooling rack to cool fully. Eat the banana bread within the next few days if kept at room temperature, or within a week if kept in the fridge. If frozen, eat within 6 months.