Preheat the oven to 350℉.
Mash the banana in a large bowl. Then, whisk in the sugar, sour cream, butter, eggs and vanilla extract in the order. In an another bowl, toss in the flour, baking soda and salt. Combine the dry and wet ingredients.
In a lined loaf pan, pour in the batter. Place in the oven for 45-55 minutes. Times will vary from oven to oven but start checking around the 45 minute mark for doneness.
When cooked all the way through, remove from the oven and allow to cool fully before slicing and serving.