Put the prawns into a bowl and season with a pinch of salt. Stir in half the turmeric, then set aside for 15 minutes to marinate.
Heat 1 tbsp oil in a large deep frying pan over a high heat. Add prawns and fry for 1 minute or so on each side until golden brown, then remove to a plate and set aside.
Add the remaining 1 tbsp oil to the pan and put back on high heat. Add potatoes and fry until golden, then add the nigella seeds and the chillies. Add the spring onions and cook until lightly browned and softened, then stir in the remaining turmeric, the ground chilli and a little salt.
Pour in 200ml water, cover with a lid and simmer until the potatoes are cooked through, stirring from time to time and adding more water if it looks too dry.
Return the prawns to the pan and cook for a futher minute or so to warm them through. Serve with warm chapatis and basmati rice.
* Nigella seeds are from Indian and Middle Eastern food shops and selected delis. Substitute 2 tsp cumin seeds.
As seen in Feast magazine, Issue 10, pg97.
Photography by David Loftus.