Skin Vaazhakkai (plantain) and cut into 1 inch cubes.
Grind coconut, fennel seeds, cumin seeds, garlic and dry chili into a fine paste by adding as little water as needed.
Heat oil in a pan, add mustard seed, spit black gram wait until mustard stop splattering. Now add curry leaves and cook for 2 min
Now add onion and cook until it turns golden brown, now add the Vaazhakkai (plantain) cubes, turmeric powder, salt to taste, add 1/4 cup water and bring to boil. Now add the ground paste and cook until the raw smell is gone.
Now simmer and cook until the water is evaporated and serve.
Getting the water is tricky just to cook the vaazhakkai (plantain) done.
Don't stir often or you will break vaazhakkai (plantain) into small pieces.