1Start by slicing the chicken breast, or chicken thighs, thinly for even and faster cooking.
2For marinade, take mixing bowl, add Mustard oil and Kashmiri Red chilli powder, mix well to bleed it's natural red colour.
3Further add the remaining marinade ingredients and mix well.
4Now add the thinly sliced chicken, mix and coat well and keep it marinated for at-least an hour or two, but incase if you have time keep it for as long as you can for more juicy and flavourful chicken, please do not go beyond 20 hours in the fridge or else the chicken may spoil.
5Smoke the marinated chicken for 4-5 minutes to impart the smoky flavour.
6Once it's been marinated and smoked, set a grill pan or any pan and grill the chicken on both the sides until golden brown in colour, you can also grill them oven for 5-6minutes at 220°C.
7Once the chicken is grilled let them cool for a while and shred them in thin strips. Keep aside for later use.
8Set a stock pot on medium heat, add oil, jeera and sliced onions, saute until onions are light golden brown.
9Further, add garlic, Ginger, Green chillies, powdered spices, whole chillies and green cardamom, mix well and cook for a minute.
10Now, add tomatoes, cashew nuts, coriander stems with its roots, salt to taste and butter, mix and cook on medium high heat for 5 minutes.
11Further lower the heat, cover and cook for 25-30 minutes on medium low heat. Stir in intervals to avoid from sticking to the pan and burning.
12Once the tomatoes are cooked, switch off the flame and let the mixture cool down to room temperature.
13Once cooled, transfer the mixture to a grinding jar and grind to a fine puree, if you're in hurry you can add ice cubes and grind it.
14Once the entire batch is pureed, strain the puree with a sieve and keep aside for later use.
15Then lets assemble the butter chicken together which is a very easily thing to do. So lets do it.