Clean the dal and keep aside. Chop onions and tomatoes. Crush the garlic with the skin.
Heat cooking oil in cooker. Add seasoning, curry leaves. Once it splutters, sauté onions, red chillies and garlic. Once onion is brown, add dal and fry for few mins.
Then, add tomatoes, tamarind, turmeric powder, and water for cooking. Cover it with lid and pressure cook for 3 to 4 whistles till the dal is cooked well.
When the pressure is off, take the dal masher or pappu guthi, mash the dal well with the red chillies. Add salt, and cook on high flame for 2 mins.
Dal is ready to serve.