Boil the chopped pumpkin and green chillies in water until the pumpkin is cooked.
Pick out the boiled green chillies. Grind them with the grated coconut, roasted Byadagi chillies, turmeric, tamarind and salt to make the masala paste, adding water as needed.
Add the masala paste to the cooked pumpkin. Check the salt, bring the curry to a boil and simmer for around 5 minutes.
Heat coconut oil in a small tadka pan. Add the mustard seeds and let them splutter before adding the curry leaves.
Pour this nesal over the curry, mix and serve with rice and happala papad.