Turn on the Instant Pot in Saute mode. Add ghee to the pot. Temper cumin seeds. When they splutter, add ginger paste, and crushed peppercorns. Saute for 30 seconds.
Add the moong dal.
Add the raw rice grains.
Add milk, water and salt. Give it a stir and hit cancel. Close the lid. Select Manual/Pressure mode and cook for 8 minutes. Release pressure naturally.
Open the lid and do a taste test. Add another cup of water mixed with milk along with salt (if needed) and mash it all well when it's still hot. Add more water if needed.
Fry cashews and whole peppercorns in ghee till they turn light golden and pour it over the Pongal.
Notes
As a thumb rule, the rice to dal ratio is 1:0.5. We like to add ¾ cup of dal because it gives the Pongal a nice texture and that's the way my mom made it. Do not add the cashews along with the other ingredients in the Instant Pot. They will lose their crispiness. Always add them after the Pongal is cooked. Roasting the lentils and rice is not required to do when making Pongal. Roasting them will not yield a soft porridge-like consistency. There is no need to even soak them. Only add crushed peppercorns rather than whole ones if you hate biting into them when eating. Keep in mind that Ven Pongal will thicken as it cools. So even if it appears a bit soggy when you open the Instant Pot, it's fine. If you feel the salt is less, mix the required salt with hot water. Add the salted water to the Pongal instead of directly adding salt. It will mix more evenly.