Preheat the oven to 180°C and cover a round or square cake pan with parchment paper (I have not tried a plumcake mold, thus I do not recommend it, while I know for a fact that you can use muffin molds if you prefer to make single-serve cakes).
In a bowl, mix the dry ingredients, then make a well in the middle and pour the vinegar, vanilla extract, and oil.
Pour the water evenly throughout the bowl, even outside the well, and mix well with a spoon, until obtaining a smooth and thick creamy batter, without lumps.
Transfer the cake batter into the previously prepared pan, and cook in the preheated oven for 35 minutes. If you are not sure whether it is done, test it with a toothpick, but do not over-bake the cake, otherwise it will be too dry.