For the black rice flour, soak the rice for 3-4 hours or overnight. Drain it and sun dry it, not necessary to dry them completely. Grind them into a fine powder.
In a mixing bowl add the black rice flour, whole wheat flour, baking powder, cardamom powder. Mix well and incorporate them nicely.
In a mixing bowl add the vinegar, baking soda, mix well and let it stand for 5 mins. Add sugar, milk, oil and mix.
Add the wet ingredients to the dry ingredients and gently fold it to make a smooth batter.
Preheat oven @180 for 10 mins. Grease a cake pan with oil and keep aside.
Pour the batter into the greased pan and tap the pan for 2-3 times. Sprinkle the chopped nuts over it.
Bake the cake for 35 mins. Start checking from 30 mins onwards. A tooth pick inserted should come out clean.
Remove from oven and let it stand for about 5 mins.
Demould it and dust the cake with powdered sugar, cut and serve with your favourite tea or coffee.
