pressure cook tur dal with enough water and turmeric powder to 4-5 whistles. open, mash it and keep it ready until use.
heat coconut oil in a pan, fry the asafoetida compound until white and keep it aside.
in same pan drop the fenugreek seeds and fry till reddish. immediately add coriander seeds and fry till reddish. together add red chillies and curry leaves. fry for half a minute.
lastly, drop grated coconut and fry in simmer until evenly reddish in color.
cool and transfer to a blender along with the fried asafoetida compound and grind to a smooth paste with little water. keep it aside until use.
in a pan, add shallots sliced, tomatoes chopped, chopped vegetables of your choice along with salt, tamarind extract, turmeric powder, water and mix well.
cook until the vegetables are done. now, add the cooked dal, prepared sambar masala, water, adjust salt if required. mix well and let it boil for 5-10 minutes until raw smell of masala goes off.
tempering: heat oil, crackle mustard seeds and add red chilli, curry leaves. fry till crisp and add the tempering to sambar.
mix well and close immediately for 5 minutes. serve hot with rice and ghee.