Method
1.	Place the fish in a large bowl.  Pour over the lemon juice and 1 tsp salt and
	mix in well, set aside for 30 minutes.
2.	Meanwhile prepare the curry base.  Heat the oil in a large heavy based pan.
	Add the onions and brown over a medium heat, the onions should be light
	brown in colour.
3.	Next add ginger and garlic and stir fry for 2-3 minutes.  Add 2 tablespoons of
	water if the mixture catches the bottom of the pan.
4.	Then add the chilli powder, turmeric, coriander powder, garam masala,
	remaining salt and 100ml water.  Cook this mixture for 2 minutes on a medium
	heat.  Now add the tomatoes, stir, cover and cook for 10 minutes, stirring
	frequently.  The oil at this stage should start to separate from the tomato
	mixture.
5.	Finally add the fish and 200ml water to the pan, stir in well and cover.
	Cook on a low heat for 15-20 minutes until the fish is tender but firm.
6.	Transfer the curry to a serving bowl and sprinkle over the chopped chillies
	and coriander.