Clean and wash the chicken pieces. Pat chicken pieces dry. Put the mustard oil, yogurt, crushed black pepper, Kashmiri red chili powder, turmeric powder, 1 tsp ginger garlic paste, 1-slited green chili, and Salt as per taste in a large bowl. Whisk everything well to make a thick and smooth marinade. Add the chicken pieces to the bowl. Coat all the chicken pieces well.

Now take 2 tbsp black mustard seeds, 1 tbsp yellow mustard seeds, 1 chopped green chili, 3-4 cloves of garlic, 1/4 cup of water, 1/2 tsp turmeric powder, 1/2 tsp cumin seeds, 1/2 tsp salt in a grinder. Grind well to make a smooth spiced mustard paste. Transfer the paste to a bowl and add 1/2 tsp of mustard oil to the paste. Mix well and add that mustard paste to the marinade chicken. Mix everything well. Keep aside for 30 minutes.

Now put 3 tbsp of mustard oil in a kadhai, and add 1/2 tsp sugar. When it will start to caramelize then add 1/2 tsp cumin seeds, onion slices, 1 bay leaf, and 1/2 inch cinnamon stick. Stir well. When onions turn to a golden brown then add 1/2 tsp Kashmiri red chili powder. mix well and immediately add marinade chicken to it. Mix well and cover it using a lid.

Cook for 15 minutes over low to medium flame. Then uncover the lid and again stir well. Then cover it again. Let it cook for another 15 minutes over low flame. Add a little amount of water if needed. Cook for 5 -10 minutes by covering it using a lid. After 5-10 minutes add some chopped coriander leaves (if available). Then immediately transfer to the plate and serve hot along with rice or chapati or Paratha.