Wash and soak the dal for 20 minutes. Chop the vazhaipoo and keep it submerged in a buttermilk mixture. Soak the Karamani overnight and drain the water. Pressure cook all the 3 ingredients separately.
The pressure cooked ingredients are ready. Mash the dal and keep aside.
In the meanwhile, soak a lemon size tamarind ball in hot water for atleast 10 minutes. Squeeze out the water and keep aside.
Heat a thick bottom kadhai, add some coconut oil, chana dal, whole dry red chillies (kashmiri red chillies used here) and coriander seeds. Saute until they have nicely roasted.
Cool it completely and grind it along with freshly grated coconut into a thick paste. Add very little water while grinding.
In the same kadhai, add the cooked vazhaipoo along with the tamarind water. Add turmeric powder, hing and salt to taste. Cook this until the raw smell of the tamarind goes off.
Add the cooked karamani or cow peas to this along with cooked dal, coconut paste and adjust seasoning (Note - We have added some salt while cooking the vazhaipoo in tamarind)
Mix well and cook for a few minutes until the gravy thickens. Add water to adjust the Kootu consistency as required. Once it reaches a boil, switch off the flame, add the tempering and serve piping hot with chapati or rice.