Preheat oven to 350˚F with the rack in the center of the oven. Fill a 12-count muffin tin with cupcake liners.
In a large mixing bowl, thoroughly whisk together dry ingredients: flour, sugar, cocoa powder, baking soda, and salt.
In a second mixing bowl, add the wet ingredients: coffee, vinegar, oil, egg, and vanilla, and whisk until well blended.
Pour wet ingredients over dry ingredients and whisk just until the ingredients come together and no dry streaks remain.
Use an ice cream scoop to portion batter, filling each cup ⅔ full. Bake 18-22 min until a toothpick inserted in the center comes out clean.
Cool 5 minutes in the pan, then transfer to a rack to cool completely to room temperature before frosting.
