Preheat the oven to 350°F / 180°C
In a medium bowl mix the flour, salt, and baking soda with a fine strainer to avoid crumbs.
In a large bowl, beat the sugar, and the butter for about 5 min until is creamy. Add one egg at a time beating thoroughly after each addition.
With a wooden spoon, mix the sour cream and the vanilla extract to the batter
Add the dry ingredients to the batter and mix them
Mash the bananas and add them to the batter and stir until the batter is smooth that holds its shape
Pour the batter to a baking pan (I used a silicon form, which you don’t need to previously prepared with butter and flour, but if you use the regular form please prepared it) and use a spoon to level the top
Bake for 65 to 70 minutes, until the toothpick comes clean. (Check every 30 min, and if you see that is becoming dark, put an aluminum paper on top)