Heat the oil in a heavy bottomed pan.
Add the onions and fry gently, stirring, until a nice dark brown colour. This should take 20 – 30 minutes
Add the garlic and fry for 30 seconds further.
Add the curry Masala and Tandoori Masala. Fry for a minute stirring all the time. If the spices are getting dry and sticking, add a splash of hot water.
Add the watered down tomato paste and reduce down to a thick paste.
Add the tinned tomatoes, vinegar, tomato ketchup and a further 200ml of water (½ tomato tin full).
Bring the mixture to a simmer then add the green pepper and chillies.
Simmer for 45 minutes before blending using a stick blender.
Bring back to the simmer and add the rest of the ingredients.
To use simply add chicken or lamb tikka, Tandoori prawns, paneer or vegetables of your choice for a vegetarian version.