In a heavy based frypan heat the oil and fry onion. Add the cashew and fry until golden brown. Add the curry paste, chilli and turmeric and stir to combine.
Add the pumpkin cubes then pour in the water and simmer for 20 minutes.
Add the chickpeas then stir in ginger. Once again simmer briefly.
Then pour in coconut milk and simmer until the curry has a thickish consistency, but the pumpkin pieces are still firm. Lastly stir in the coriander to serve.