Whisk together the flour, salt, baking powder, and baking soda in a medium mixing bowl and set aside.
Whisk the sour cream, instant coffee granules, brewed coffee, and vanilla in a separate medium mixing bowl.
Beat the butter, granulated sugar, oil, and brown sugar in a stand mixer fitted with the paddle attachment on low until smooth.
Adjust the mixer's speed to medium-high and, after 5 or 6 minutes, scrape down the bowl once or twice to ensure the mixture becomes very light and fluffy.
Bring the mixer speed to medium, add the eggs one at a time, and beat thoroughly after each addition. You should clean the mixer's sides.
Mix in roughly one-third of the flour mixture on low speed until the flour is practically gone.
Add half of the sour cream mixture and beat just until combined.
In two additions, alternately add the remaining flour and sour cream mixture.
When no more flour can be seen, turn off the mixer and take out the bowl.
In order to ensure that the batter is thoroughly mixed, it should be folded over and scraped down with a flexible spatula several times.