In a mixing bowl, add the orange juice, the vinegar and the baking soda, mix until the mixture foams,
Add the vegetable oil, water and sugar to the rest of the ingredients,
Add the flour, cocoa, baking pwder, salt and vanilla to the mixture,
Whisk until everything is combined.
Divide the mixture in cupcake liners
Bake for 30 minutes at 170 C (340 F)