Peel ginger, trim green chillis and blend to a paste with garlic. Trim green chillis, blend to a paste. Peel and dice the onions. Blend the tomatoes. Crush the ajwan seeds with the back of a spoon. Toast the desiccated coconut until light golden brown. Dice the chicken thighs into 2.5cm pieces.
Heat the oil in a pan on a medium heat, then add the cumin and mustard seeds, sizzle for 2 minutes, then add the curry leaves.
Add the onions and cook for 4-5 minutes until caramelised. Add the chilli, ginger and garlic paste, then cook for another minute.
Add the blended tomatoes, turmeric, chilli powder, ground cumin, ghee butter and salt, mix well, then cover and cook for 3-4 minutes, stirring every minute.
Once the masala splits at the edge, add the chicken and coat well in the sauce, cooking for 3-4 minutes.
Add the water and bring back to boil. Add the crushed ajwan seeds, coconut milk, dried fenugreek leaves and garam masala. Roughly chop the coriander, add to the masala, then mix well. Cook for 5-6 more minutes, then serve.