Mash the bananas then whisk them with the sugar and oil. Add in the salt, vanilla, cinnamon, and sour cream and whisk well. Whisk in the eggs.

Add the flour and baking soda and fold with a rubber spatula until combined. Cover with plastic wrap and set in the fridge overnight (or at least for 4 hours).

When you are ready to bake, preheat the oven to 400 F. Line two 12 cup muffin tins with six liners each, alternating cups so that no two muffins will bake next to each other.

Bake for 20 minutes, until the tops spring back when pressed.