Soak the dals for 3-4 hours. Drain and grind them to make a thick batter—do not add too much water. Add a paste of green chilies and ginger, crushed black pepper, and salt. Mix well.

Heat oil in a deep pan. Shape the batter into small or large vadas as you prefer, and fry them until golden brown.

To make the rasam, boil the toor dal with turmeric and salt until soft. In a separate pan, heat oil and add mustard seeds, curry leaves, garlic, chili paste, and onions. Sauté for 2 minutes.

Add tomatoes and a tablespoon of urad dal. Mix well. Add turmeric powder, chili powder, and salt, and sauté for another 2 minutes. Add tamarind paste and a pinch of asafoetida (hing), mix, cover, and cook for 2-3 minutes. Then add the cooked dal.

Add rasam masala and simmer everything together, covered, for 2-3 minutes. Pour the rasam into a serving bowl, top with the vadas, and serve hot. It's very tasty!