Soft Vanilla Cake in Tea Cup

To make 4 cupcakes:

1 cup of flour

1 tablespoon of baking powder

1/2 tablespoon of baking soda

1/2 tablespoon sugar

1/4 cup of oil

1/2 cup of yoghurt / curd

1/2 tablespoon of vanilla essence

chopped nut (optional)

1/4 cup of water

4 disposable paper tea cups