In a vessel half cook the yam pieces adding little water. When it is half cooked, add long beans pieces, turmeric powder and little salt. Cook both the vegetables till they become tender in medium flame.
Grind the grated coconut, cumin seeds and green chillies in to medium fine paste adding little water.
Add the ground masala to the cooked vegetables. Mix well. Avial should be thick in consistency compared usual curries. So add water accordingly at this stage.Add additional salt needed and bring it to boil.
At the end add the whisked curds and mix it well. Do not cook after adding curds.
Now in a seasoning pan add a tbsp of oil, mustard seeds, urad dal, broken red chilly and curry leaves. when the mustard seeds splutter add the seasoning to avial. Now avial is ready to be served. It tastes awesome with hot steamed rice.
