Heat oil then add sliced onion into it, when onion changes its color into transparent add chicken.
Add ginger/garlic paste and stir carefully then add black pepper, crushed pepper and vinegar.
Mix together all the ingredients and add a little amount of water into it and let the chicken get tender.
Cover the lid after some time then add tomatoes and chillies(optional)
Once the chicken is ready add two tsp of vinegar just to retain the aroma and after one minute turn the heat off and delicious chickenvinegar is ready.