In a bowl mix the chicken with the pepper, salt, oregano, celery, onion, garlic and peppers, let it marinate for at least 1 hour.
In a casserole, heat up the oil, add the sugar and let it cook until golden brown. Add the chicken (reserve the marinade) and cook until browned all sides.
Keep stirring constantly. Add 2 tablespoons water, cover and let it cook for 12 minutes (adding water from time to time for avoiding it to burn).
Add the remaining ingredients (except the tomato paste), cover and let it simmer until the vegetables are tender.
Add the tomato paste and 1/2 cup water, simmer over low fire until getting a slightly thick sauce, adjust the seasonings and serve garnished with coriander and together with white