With the rack in the center of the oven, preheat to 425°F. Line 16 muffin tins with papers. Sift together the flour, baking soda, cinnamon and salt in a bowl and set aside.
With a stand mixer fitted with the whip attachment, beat together the sugar and eggs on medium speed until light and fluffy, about 5 minutes. Switch to low speed and slowly drizzle in the oil, taking your time.
Add the bananas, sour cream, and vanilla, and continue to mix on low speed just until combined.
Use a rubber spatula to fold in the flour mixture until thoroughly combined. No flour streaks should be visible.
Pour the batter into the muffin tins and bake for 5 minutes at 425°F then turn the heat down to 325°F and continue to bake for 15-20 minutes.
The muffins should be golden brown on top, a toothpick will come out clean and the muffins will spring back when you gently press down. Let cool on a wire rack for 5 minutes, then remove the muffins from the pan and let cool completely on the wire rack. Enjoy!