Preheat the oven to 175C| 350 F degrees.
Line a 22x 12 cm | 10 x 4 inch loaf pan with parchment paper.
In a medium bowl, mix together the cacao powder, flour, sugar, baking soda, and salt together. Set aside.
In a separate bowl, mix together the coconut oil, espresso, vanilla, vinegar, and water until well combined.
Stir in the wet ingredients into the dry ingredients and stir until just combined.
Pour the batter into the baking pan and bake for about 45 minutes, or until a toothpick inserted in the middle comes out clean.
Let cool down for 5 minutes into the pan, then transfer to a wire cooling rack.
Cool down completely before slicing.