Peel the skin of pumpkin and thinly slice into medium pieces.
Heat oil in a pressure cooker.Slice the onions.
Add cumin seeds to the cooker and when they change colour, add onions. Sauté till brown. Slit green chillies and add.
Combine mustard seeds and fennel seeds in a grinder jar. Grind coarsely and add to the pan. Mix well. Add pumpkin pieces, salt, coriander powder, turmeric powder and red chilli powder. Mix well.
Add a little water and mix well. Add amchur, sugar and melon seeds. Mix, cover and cook on low heat till 1-2 whistles are given out. Remove from heat and let it stand, without removing the lid, for 4-5 minutes. Then open the lid, mash lightly and serve hot.