Heat the ghee over a medium heat and add the mustard seeds, cardamom, cinnamon, chilli and curry leaves. Simmer for 1-2 minutes, stirring regularly. Add the curry paste, turmeric and cook for another minute.
Add the cauliflower and coat each floret with the spice mixture, add the coconut milk, lemon zest and stir.
Bring to a boil and simmer for two minutes before adding your fish to the pan. Gently push the pieces down so they’re covered in sauce. Close the lid and simmer for a few minutes until the fish is just cooked.
Squeeze over the lemon juice and scatter over the coriander leaves. Top with curry leaves and serve with steamed rice.