1) Chop the onions and saute in the butter until golden.
2) Add the curry powder and fry gently for a minute or two.
3) Add the garlic paste, ginger and chillies and fry for a minute or two.
4) Add the tomatoes and simmer the sauce for 30 minutes.
5) Whilst the sauce is simmering cut the tilapia into chunks and roll in seasoned gram flour.
6) Fry the tilapia pieces in the coconut oil and set aside.
7) Once the sauce is cooked through add the tilapia pieces and simmer for a few minutes more.
8) Serve sprinkled with the coriander leaves.