Add oil to inner pot in your Instant Pot and press the saute option.
When the oil is hot add mustard seeds and urad dal..
As the mustard seeds start to sputter, add curry leaves and green chilies and stir well for a minute.
Add onions and continue to saute for at least a minute.
Now add tomatoes and let them soften up and then add potatoes.
In about a minute, add turmeric and sambar powder and stir well for an even mixture.
Add split red lentils, tamarind, jaggery, 2 ½ cup water, and salt.
Close the lid of the instant pot. Turn the steam release handle to sealing position. Press on Pressure cooking( high pressure) setting and set the timer for 7 minutes.
When time is up open the lid using quick release option or you could also let it cool down naturally.
Garnish with cilantro and Potato Onion Sambar is ready!
Pair it with steamed rice, Dosa or even rotis.