Cook toor dal in a pressure cooker until soft and mushy.
In a large pot, cook mixed vegetables with turmeric and salt until tender.
Add cooked dal, chopped tomatoes, and tamarind paste to the vegetables.
Stir in Udupi sambar powder and bring to a boil.
Simmer for 10-15 minutes, adding water if needed for desired consistency.
Add jaggery if using, and adjust salt to taste.
For tempering, heat oil in a small pan. Add mustard seeds, fenugreek seeds, dried red chilies, and asafoetida. Let it splutter.
Pour the tempering over the sambar and garnish with curry leaves.