Add the onion, garlic, and ginger to a mini food processor and blend to a paste. Add a splash of oil to loosen if needed.
Heat the ghee (or oil) in a large frying pan over a high heat. Add the onion mixture and fry for 3-4 minutes, stirring occasionally, until starting to brown at the edges.
Add the chicken and cook for 2-3 minutes, stirring often, until sealed.
Turn the heat down to medium and add the cinnamon, madras curry powder, paprika, ground fenugreek, tamarind paste, salt, and pepper. Cook for 1 minute, stirring constantly.
Add in the passata and tomato puree and bring to the boil.
Add the coconut milk. Stir and bring to the boil, then simmer for 25 minutes.
Serve with fresh coriander and boiled rice.