Preheat your oven to 350°F (175°C). Line your muffin tin with cupcake liners.
In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, cocoa powder, baking soda, and salt until combined.
In a separate bowl, combine the hot water, vegetable oil, vinegar, instant coffee granules (if using), and vanilla extract. Mix until the coffee is dissolved.
Pour the wet mixture into the dry ingredients. Using a whisk or spatula, mix gently until just combined. Be careful not to overmix; a few lumps are okay.
Divide the batter evenly among the cupcake liners, filling each about 2/3 full. Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted into the center comes out clean.
Once baked, remove the cupcakes from the oven and let them cool in the tin for about 5 minutes. Then, transfer them to a wire rack to cool completely.
Once completely cooled, frost your cupcakes with chocolate buttercream frosting or your favorite frosting recipe. Get creative with decorations if you wish!