Cook the toor dal (split pigeon peas) in a pressure cooker adding double the water.
In a roasting pot, dry roast chana dal (Split chickpeas), fenugreek seeds, coriander seeds, grated coconut till they become golden brown. Add coconut at the end as it takes less time to roast.
Puree it finely in the blender along with red chili powder adding little water.
Chop eggplant, drumstick (3 inch size). Julian onions.
In a pot add 1 cup water. Add all the chopped vegetables. Cover it and cook for 10 minutes.
Add tamarind paste and cooked dal.
Add the puree and readymade sambar masala.
Add sugar, salt and water. Let it come to a boil.
In a different pot, heat oil and add mustard seeds. When mustard seeds starts to sputter, add turmeric powder, asafoetida, red chilis and curry leaves.
Add the above tadka to sambar. Let it boil for 5 minutes on low heat. Serve hot.
Notes
The vegetables I have used in the sambar are the ones my family prefer. You can also use red pumpkin, carrot.