Grease or line a 9-inch round/square pan or a loaf pan and keep aside. Pre-heat the oven to 180 degree C.
In a bowl, mix together the flour, cocoa and baking soda.
In another bowl, measure the water.
Add oil.
Add vinegar.
Add vanilla and coffee powder.
Add the sugar and mix well.
Start adding the dry mix to the wet mix, one tbsp. at a time so as to not create lumps. Keep whisking till you get a smooth batter.
Pour the batter into the prepared pan and top with nuts/chocolate chips if you like.
Bake for 35-40 minutes or until a toothpick inserted into the center of the cake comes out clean.