Heat the ghee in a karahi or heavy-based pan over medium heat. Add the tomatoes and fry well for 5-6 mins or, until soft and starting to break down, stirring occasionally. Add the whole green chillies, black peppercorns and 1 tsp salt and fry for 2-3 mins until fragrant. Add the chicken and stir to coat well.

Cover with a lid and cook for 15-20 mins then remove the lid and cook for further 20-25 mins until thickened, most of the liquid has evaporated and the tomatoes are broken down and sticky. Season to taste and garnish with the butter, ginger, and coriander. Serve with lime wedges to squeeze over the top, and rice, naan or roti, if you like.