Take a bowl with oil in it. Add powdered sugar, milk and vinegar in it. Mix this mixture well till it becomes light. Keep this mixture aside.

Meanwhile take any vessel or a tin and grease it with oil.

Then take a pressure cooker or any aluminium vessel. Put a plate or a stand at the bottom of the vessel or the pressure cooker and keep it on the gas on low flame for 10 minutes for preheating.

Now take the liquid mixture which was already prepared and kept aside. Add all purpose flour, coco powder, baking power and baking soda into it.

Stir this batter lightly and slowly in one direction only. Make sure that there are no lumps in the batter. The consistency of the batter should be medium.

Pour this batter into the tin or vessel which is already greased with oil. Keep it into the preheated pressure cooker or any aluminium vessel.

Cover this vessel or pressure cooker with any plate or glass lid.

If you are using pressure cooker then please remove ring (gasket) and remove whistle also.

After 40 minutes, check the batter by inserting a tooth pick or a knife. If the batter leaves on the knife or the tooth pick, then bake it for another 10 minutes.

Again check the batter after 10 minutes. If the knife or the tooth pick comes out clean, then your cake is ready.