In a large saucepan, heat 2 tbsp rapeseed oil over a medium heat and cook the chicken pieces, then set aside. You may need to do this in batches.
Heat the remaining oil in the pan over a medium heat add the star anise, bay leaf, coriander seeds and fennel seeds and cook for around 40 seconds until the seeds start to pop in the pan.
Add the onion and fry for around 2 mins, then add the garlic and ginger paste and stir together.
Add the green chilli's, ground coriander, methi leaves, curry powder and chilli powder and cook for another 30 seconds.
Add the passata and 250ml of the base curry and stir together.
Add the chicken, remaining base curry sauce and stock. Stir together and leave to simmer for around 15mins. Stirring occasionally ensuring the chicken doesn't stick to the base of the pan.
Add the yoghurt, garam masala and coriander leaves and stir together.
Serve with plain rice, naan and maybe some sag aloo on the side.