1. Cut chicken, separate legs and thighs, back and split breast. 2. Heat oil over high heat. Add onions fry till golden brown. Take care not to burn them. 3. Add garlic, ginger and tomatoes. Fry till a smooth paste. 4. Add chicken, add water, bring to a boil, add salt. Cover pot and lower heat. Add chili to make it hot if desired. 5. Stir constantly to avoid burning and coat the chicken pieces evenly. 6. After the chicken is done, add vinegar and cook for another 5 minutes on a very slow fire. Sprinkle Garam Masala and serve.