Heat oil in a pan, add onions and fry until golden brown. Then add ginger-garlic paste and sprinkle water to avoid burning.
Add tomatoes, curry leaves, turmeric powder and pepper powder, sauté for about five minutes.
Add salt and sauté till the tomatoes are mashed and oil leaves the masala. Then add chicken pieces and water to cook. Cook on medium flame until chicken is done. Add vinegar for taste.
Garnish with coriander leaves and serve hot.