First cook the dals and turmeric in a pressure cooker or Instapot until its cooked soft.
In a pan roast the dals, masalas, chilis and coconut until golden brown and the aroma is released.
Then grind all this with the onion and tomato in to a smooth paste.
Once the dal is cooked nicely and the cooker /IP is ready to open add in the veggies, green chilis and the tamarind paste and give it a quick stir.
Let it all boil for a min and then add the ground masala mixture and the salt to the cooker.
Give it a quick mix and leave it in the cooker for couple of whistles.
This will allow the veggies to cook enough and the take away the raw smell of onion from the ground paste.
Once the pressure is down open the cooker and add in the jaggery and mix well. Jaggery will melt for the heat of the sambar.
Add the tadka of Mustard, split red chilis and curry leaves to the sambar and enjoy with hot Idlis or vadas or even with rice.