Switch on the saute mode on your Instant pot and add the moong dal to it. Roast it until nice and fragrant for a couple of minutes. Remove it.
Start instant pot in sauté mode and heat ghee in it. Add cumin seeds, black peppercorns, asafoetida, curry leaves, and cashews. Saute till the cashews are lightly roasted. Take out half of the tempering and reserve for later. Add green chili and ginger.
When the ginger turns golden brown, add rice and moong dal. Saute for 2-3 minutes.
Add water and salt. Close lid with vent in sealing position. Change the instant pot setting to rice mode, which defaults to low pressure cooking for 12 minutes.
When the instant pot beeps, let the pressure release naturally for 10 minutes, then manually release the remaining pressure (10 minute NPR).
Open the instant pot, and serve pongal. Top with reserved tempering with roasted cashews. Enjoy hot with sambar and chutney!