First chop and immerse the Banana Stem or Vazhaithandu pieces in a mixture of buttermilk and turmeric powder.
Soak the lentils for 10 minutes (while chopping the banana stem).
Discard the buttermilk water and rinse once quickly.
Add salt and turmeric powder. Pressure cook the Banana Stem and the dal separately until the Banana Stem is slightly mushy. Do not overcook.
Prepare the Coconut gravy by grinding chopped pieces of coconut, whole red chillies and jeera or cumin seeds.
Heat a Kadhai or pan, add all the 3 ingredients together, adjust the consistency with required quantity of water and simmer for 5 minutes.
Switch off the flame and prepare for tempering.
Add a tempering in coconut oil with curry leaves, urad dal and mustard seeds along with whole red chillies. Serve piping hot with chapati or rice.