Heat the oil or ghee in a karahi or heavy bottomed pan.
Add the onions and fry on a gentle heat until soft and lightly browned.
Add the garlic and ginger and cook for 30 seconds.
Add the curry Masala and gently fry for a further 30 – 40 seconds. Stirring all the time to avoid the spices catching.
Add the watered down tomato paste and turn up the heat. Reduce until you have a thick paste.
Add the chicken and turn to coat in the paste.
Add the tinned tomatoes and bring to a simmer.
Turn the heat so the curry is just simmering. Cover with a lid and gently cook for 15 minutes.
Remove the lid. Stir in the sugar, lemon juice and salt to taste.
Bring back to a simmer and continue to cook for 10 minutes or so or until the chicken is cooked through.
Stir in the fresh coriander.
Serve with rice and Indian bread.