In a heavy bottom pan, roast the moong dal without any oil until it aromatic and light brown. Now add the rice as well and give it a mix. Fry for about 2 minutes until the rice is heated through.
Transfer this rice/dal mixture in a vessel that you are going to use to cook it (I use the cooker vessel that I place inside the cooker), and wash it well.
Add enough water (I use about 5-6 cups of water) and cook it along with turmeric powder in a pressure cooker until the rice/dal is cooked very well and mushy.
I usually let it cook for 4-5 whistles in the cooker. Also, the amount of water I use is more than what I would use normally. This ensures that that the rice is cooked well.
Meantime, grind the black pepper and cumin seeds into a coarse powder in a spice grinder. You could add everything whole and not grind, but in that case everyone picks through the pepper and do not eat it. When they are in the ground form we eat it and the goodness of it is utilized.
Once the rice is cooked, mash it well with a potato masher or a heavy spoon. Heat the ghee in a pan and add the ½ teaspoon of black pepper, curry leaves, asafetida, ginger and cashew nuts and fry for a minute. Now add the ground cumin/pepper mixture and mix well.
Add the cooked rice/dal along with salt needed and mix well. Adjust the consistency by adding a little water if needed. I usually have my pongal on the thinner side as it hardens upon cooling. If preferred, add a tablespoon more of ghee on top and serve steaming hot with Gothsu or Chutney.