Mix the grated coconut, black pepper, garlic, cumin seeds and turmeric in a mixer to a fine paste, traditionally it is mashed in a special Kerala stone tool called the Ammikallu. Cook pumpkin in 2 cups of water for about 5 minutes . Add 1 cup coconut paste and salt and bring it to boil. Heat oil in a frying pan and temper with mustard seeds. After mustard seeds splutter, add rest 1/2 cup grated coconut, urad dal and curry leaves and wait till urad dal becomes crispy. Add this as tempering to pumpkin curry and mix lightly. One could 1 or 2 table spoons of sugar to make the curry more sweet and suitable for children.