Switch on the Instant Pot and turn to sauté mode ON.
Add oil, once hot add mustard, cumin. Stir and fry for few seconds and let the mustard splutter for few seconds.
Now add curry leaves, asafoetida and saute for few seconds.
Add onion followed by ginger, garlic and sauté for a couple of minutes or until the onion starts to soften.
Stir in turmeric.
Add tomatoes, sauté and cook for 1-2 minutes or just until tomatoes start to soften.
Now add spinach, sauté and cook for a minute.
CANCEL the sauté mode.
Add lentils, water and mix well.
Close the pot with lid, ensure the pressure release valve is turned to the SEALING position.
Select pressure cook mode, HIGH for 5 minutes. Once finished, let the pressure release naturally (NPR).
Turn pressure valve to VENTING position and wait until the FLOAT VALVE goes down completely. Take the lid off the pan, add lemon juice, salt and mix until dal is well mashed.
Enjoy piping hot palak dal with steamed rice.