In a cooking pan, heat oil, then saute' ginger, garlic, onions and tomatoes.
Add chicken to the mix, then saute' for 3 to 5 minutes. Add salt and then mix.
Add ground pepper and then water. Bring it to a boil for 30 to 40 minutes or until the meat is tender.
Add fish sauce and let it cook until chicken is light brown. Add the scallions and pechay, then let it simmer for 5 to 10 minutes.
Add the rest of the scallions to the mix and let it simmer until you achieve your desired tenderness of the meat and the sauce reduced. Add more water if necessary.
Adjust seasoning according to your preferred taste. Serve it in a bowl and enjoy it hot!