In a pressure cooker, add washed toor/tuvar dal along with diced tomatoes and green chilly (cut in half). Add enough water so that everything is covered. Pressure cook it for 3 – 4 whistles.
After the pressure has dropped, open the lid of the pressure cooker and mix the dal/pappu well. The tomatoes would be cooked and the dal – neither too pasty/mushy nor too grainy. Add salt, red chilli powder and turmeric powder. Mix well.
Let this mixture be on slow boil. Add some water if it’s too thick.
In a small pan, heat oil. Add mustard and cumin seeds along with the dried red chilli (cut in half). As the mustard and cumin splutter, add asafoetida and curry leaves. Fry for ten more seconds. Add the tempering to the boiling pappu/dal. Remove it from heat.
Serve hot with rice and ghee/clarified butter on top. Any vegetable side dish would be apt along with some fryumps or oora mirapakalayu.
Notes
If you don’t want a spicier version, you can skip green chilly.
Instead of adding red chilli powder, sambar powder can be added as well.