Select sauté on the instant pot and adjust to normal.
Add oil to the pot.
When the oil is hot add the cumin seeds, mustard, and fenugreek seeds.
When the seeds begin to splutter, add curry leaves, whole dried red chili peppers, and asafoetida.
In 30 seconds, add the chopped onions and sauté. Stir to prevent the onions from burning.
When the onions turn golden in roughly 2 to 4 minutes add the ginger garlic paste. Stir
Add the diced tomatoes and sauté for a minute until they get mushy.
Add the chopped vegetables and stir.
Add the sambar powder, red chili powder, 1/2 cup water, and salt. Give it a good stir.
Then add the toor dal, and remaining 3.5 cups water and stir well. Make sure nothing is stuck to the bottom of the pot and scrape the bottom of the pot well.
Secure the lid on the pot.
Select manual and cook at high pressure for 7 minutes.
Use natural pressure release. The natural pressure release should take about 10 minutes.
Open the lid.
Add the tamarind concentrate. Stir well.
Transfer in a serving bowl immediately.