Heat the oil in a sturdy frying pan or karahi over a medium heat
Add the fennel and cinnamon, fry for 1 minute
Add the onions and curry leaves and cook for 10 minutes. The onions should be soft and golden in colour
Stir in the garlic, ginger, sugar, salt and all of the Chettinad spice blend
Fry for a further 1-2 minutes
Add the chopped tomatoes and cook for about 8–10 minutes, stirring often. Let the tomatoes completely breakdown to give you a thick aromatic sauce
If needed, add more water to stop it sticking to the pan
Add the chicken and stir around for 1-2 minutes, ensuring the chicken is fully coated in the sauce
Let the chicken cook through
Optionally sprinkle with chopped coriander before serving
Serve with plain boiled basmati rice