1. Drain the soaked urad dal and grind it to a smooth batter with minimal water.
2. Add salt, chopped ginger, green chilies, onion, and curry leaves to the batter. Mix well.
3. Heat oil in a deep fryer. Shape the batter into small donuts and deep fry until golden brown.
4. For sambar, heat oil in a large pot. Add mustard seeds, cumin seeds, dried red chilies, and asafoetida. Sauté for a minute.
5. Add chopped vegetables and sauté for a few minutes. Add cooked toor dal, tamarind pulp, sambar powder, turmeric powder, and salt. Cook for 10-15 minutes.
6. Serve the hot medu vadas with sambar.