Mix the prawns with the lime juice and turmeric in a bowl and allow to marinate.
In a blender add the ginger, garlic, green chillies and coconut. Then add some water and blend to a smooth thick paste.
In a frying pan, add 1tsp of the oil and fry the prawns for around 1 minute on each side. When they start to colour remove from the pan and put them on a plate lined with kitchen roll to drained the excess oil.
Heat a non-stick pan on high heat, once hot add the remaining oil, mustard seeds and curry leaves and them sizzle.
Add the garlic and ginger paste, and fry on a medium heat for 5-6 minutes, stirring occasionally so it doesn't stick to the bottom of the pan.
Add the salt, ground coriander, tamarind chutney, tomato puree and mix well. Cook for another 2 minutes.
Pour in the coconut milk and water, bring to a boil then reduce the heat to a simmer. Add the prawns and simmer for 5-8 minutes, then garnish with curry leaves and serve with plain boiled rice.