Marinate chicken in vinegar for an hour. Then heat oil in a pan or kadhai. Temper the oil with few green cardamoms until they begin to change color. Add minced onion; cook and stir until translucent. Stir in the garlic and ginger paste, cook until the onions become brown. Add chicken and red chili paste or powder to the skillet. Mix well and cook until the chicken is tender and cooked thoroughly. Add yogurt along with black pepper powder and mix properly. Add salt and a pinch of sugar, to taste. Add cashew paste and mix it thoroughly with the gravy. Finally, stir in some fresh cream. Cover and simmer for fw minutes. And your Dum Murgh Kali Mirch is ready!!!