Preheat the oven to 200 degrees Celsius, use a sharp knife to slice the chicken into smaller pieces, then place then in a bowl. Add in the rest of the ingredients for the chicken then toss properly to coat. Cover the bowl then let the chicken marinate for about one hour.
Next, place the marinated chicken into a baking sheet, place the baking sheet into the preheated oven and cook for about twenty minutes. In the meantime, place a non-stick skillet over medium heat then add in the ghee.
Once the ghee melts, add in the chopped onions, ginger, coriander seeds, mustard seeds, and cumin seeds then cook for about five minutes. Add in other ingredients like the coconut milk and all the spices on the list, stir properly to combine then add in the tomato paste.
Stir the sauce one more time, decrease the heat to low then simmer for about fifteen minutes until the sauce thickens. Add in the cooked chicken, stir to combine then take out of the heat. let the meal sit in the pan for about five minutes to cook in the residual heat, serve.