Method
1.	Char grill the tomatoes and green chillies.  To do this on an open flame, spear
	each of them with a fork and rotate in the flame until the skin is charred black.
	When all are done, place on a tray and cover with cling film and leave to cool.
	Once cooled, remove the cling film and the skin should peel off easily.
2.	Lightly crush the cumin seeds in a mortar and pestle.
3.	Place all the ingredients in a blender and whisk until semi-smooth.
4.	Chill for at least an hour before serving.