Chop the pumpkin or squash into 3cm chunks and cut the ginger into matchsticks. Pick the coriander leaves and finely chop the stalks. Pour a good lug of groundnut oil into a large saucepan and place on a high heat. Add the ginger, garlic, red chilli and shallots, then reduce to a medium heat. Cook until golden, stirring occasionally, then add the mustard seeds, curry leaves, and coriander stalks and fry until the curry leaves go crispy. Add the turmeric, tomatoes and coconut milk. Bring to the boil, then add the pumpkin and chickpeas. Reduce to a low heat, cover with a lid and simmer for 45 minutes. Check occasionally and add a splash of water if it looks a bit dry. When the time’s up, take the lid off and cook for a further 15 minutes or so until the sauce is lovely and thick. Scatter with coriander leaves and serve with rice, naan bread and chutneys and dips on the side.