Assemble all the ingredients for the dal in a pressure cooker or large heavy-bottomed pot. Cover with water and add at least 2 cups more to ensure the dal gets cooked through and soft.
Cook for 4 whistles and allow to cool, and then mix well and mash with a pappu gutti or wooden masher. Alternatively, simmer until the dal is soft and mashes easily between your fingers.
Add salt to taste.
In a separate tempering pan, heat the oil until almost smoking. Then drop in the dry spices and allow them to splutter.
Follow immediately with curry leaves, garlic and the small diced onion.
Fry until the garlic and onion are beginning to brown and pour the tempering over the cooked dal.
Mix well, simmer for a few minutes longer, and serve hot with a soft rice and ghee on the side.