Blend coconut, jeera and green chilli to a smooth paste by adding water as needed. Keep aside.
In a large pot, cook potatoes with salt and water. Further add all the other vegetables.
Add curry leaves, turmeric and mix well.
Cover and cook the veggies till they are cooked well.
Add the coconut masala and cook until the raw coconut smell goes away.
Turn off the flame and add half cup of sour curd. Set aside.
For tempering, heat 2 tsp coconut oil, add mustard seeds, urad dal, dried red chillies, curry leaves and asafoetida. Allow to splutter.
Pour the tempering onto the avial and mix well.
Serve hot along with rice.