Rinse and wash dal with plain water for 3-4 times or until water runs clear.
Soak dal with warm water for 20 minutes, drain the water and keep it aside.
Plug in Instant Pot, turn sauté mode ON and add oil.
Once oil is hot, add mustard, cumin and let it splutter for few seconds.
Now add red chillies, asafoetida, garlic and sauté for few seconds until garlic starts to turn light brown.
Add Curry leaves, green chillies and sauté for few seconds.
Now add onion and sauté for 3-4 minutes until they start to turn soft.
Stir in turmeric and then turn saute mode OFF.
Add mango, dal, water and close the pot with lid.
Turn the knob to SEALING position.
Turn pressure cook mode ON, set timer to 15 minutes at high pressure.
Once done, let pressure release naturally (NPR) for 10 minutes. Then turn the knob to vent position, wait until pin goes down.
Take the lid off the pot, add salt, coriander and mix well.
Mash dal with back of the ladle.
Enjoy piping hot dal with any rice of your choice.