Preheat the oven to 350°F.
Line a 12-cup muffin tin with paper or foil liners.
In a medium saucepan, add the butter, coffee, and vegetable oil over low heat.
Stir until the butter is melted and all ingredients are combined.
Add the butter to the bowl of a stand mixer and beat at low speed until smooth.
Add the egg and beat until incorporated.
Add the buttermilk, vinegar and vanilla and beat until smooth.
Scrape the sides and bottom of the bowl and mix again for 1 minute.
In a large bowl, sift the flour, sugar, cocoa powder, baking soda, and salt together.
Slowly add the dry mixture to the butter mixture.
Mix on low for 2 minutes then increase to medium for another 4 minutes.
Scrape the sides and the bottom of the bowl and mix again on medium for 1 minute.
Scoop the batter using a medium sized ice cream scoop into the lined muffin tins, filling them about
three-fourths full.
Bake the cupcakes in the center of the oven for about 25 minutes, until springy.
Insert a toothpick in the center of the cupcake, if it comes out clean it is fully baked.
If not, bake for another 3-4 minutes.
Cool the cupcakes while still in the muffin pan for 10 minutes.
Remove the cupcakes from the pan and put on a wire rack to cool completely.