Cut  tomato, onion into small pieces. Add some ginger, garlic and make paste.Cut thin slices of green chilli.Mix red chilli powder, salt, turmeric powder, yogurt, 1 tbsp. soya sauce, 1 tbsp cornflour and 2 tbsp oil. Marinate the chicken with this mixture for half an hour. Then apply onion-tomato paste to the chicken and again marinate for half an hour. Heat oil in a pan. Add green chillis, white pepper powder and black pepper powder and fry for 30 secs. Add chicken marinade and fry until half cooked. Stir ocassionally. Mix rest of the cornflour and soya sauce in water and add to the chicken. Add little water (about 2-3 cups) to make thick gravy and bring it to boil. Cover and cook for 8-10 mins on low flame. keep a constant watch.