Heat oil in a kadai add grated coconut, turmeric powder, chilli powder and coriander powder,saute for 2 minutes.
When it turns golden brown switch off stove.
Grind coconut mix, onion in a mixer with little water to form a smooth paste. Keep it aside.
Heat oil in a kadai add onions, and bitter gourd sauté for 2 minutes.
Add green chilli, coriander powder, chilli powder and turmeric powder sauté for 2 minutes.
Then add the ground coconut mix and 1 cup water to this kadai. Boil for 3 minutes.
Heat oil in another kadai add mustard, when it splutters add red chilli and curry leaves sauté for a minute .
Add this to bitter gourd mix, boil for 2 minutes.
Now nadan pavakka theeya is ready.