Cook the lentils until very soft and mushy.
In a medium saucepan, heat 2tsp oil and add all the tempering ingredients. Once the seeds start to splutter, add onions and green chilies. Cook until onion starts to turn translucent.
Add the chopped greens, cover and cook until they wilt and cooked through.
Add tomatoes, tamarind paste and salt, cook for another 5 minutes or until tomatoes turn mushy.
Stir in cooked lentils and ½ - 1 cup of water (depending on the desired consistency) and simmer on medium heat for 5 minutes.