Cook the toor dal: Pressure cook the dal with 3 cups water and turmeric powder for 4-5 whistles until completely soft. Mash well and set aside.

Prepare tamarind extract: Soak tamarind in 1 cup warm water for 10 minutes. Squeeze and extract the pulp, discarding the solids.

Cook vegetables: In a pot, add chopped vegetables, green chilies, and enough water to cover. Cook until vegetables are tender but not mushy.

Make sambar base: Add tamarind extract, sambar powder, and salt to the cooked vegetables. Simmer for 5-7 minutes.

Combine dal and vegetables: Add the mashed dal to the vegetable mixture. Adjust consistency with water if needed. Simmer for 5 minutes.

Prepare tempering: Heat oil in a small pan. Add mustard seeds, cumin seeds, fenugreek seeds, and let them splutter. Add asafoetida and curry leaves.

Finish the sambar: Pour the tempering over the sambar. Garnish with fresh coriander leaves. Cover and let it rest for 5 minutes before serving.