To make the spice paste for the erissery, grind together 1/2 cup coconut, cumin seeds and red chillies, adding a little water if required, to a fine paste
Keep aside till needed.
In a heavy bottom pan, add the chopped pumpkin pieces (discard the peels) along with a cup of water and turmeric.
Cook till the pumpkin is tender and the water has almost dried up.
Add the coconut and spice mixture and let it cook for about 4-5 minutes at low heat. Take off heat.
In a small tadka pan, heat the oil, add the mustard seeds and when they crackle add the urad dal and let it brown, turn off the heat and add the curry leaves and after a minute pour this over the cooked pumpkin.
In a separate pan, toast the 1/4 cup coconut without oil constantly stirring and paying attention to it so that it turns a nice even brown. Add to the pumpkin mix, stir and the erriserri is ready to serve.