In a wok, heat oil over medium heat.
Add onions and garlic and cook until onions are translucent in colour.
Add chicken and cook until chicken turned light brown in colour.
Add tomatoes and continue to cook everything until tomatoes are softened.
Add water and bring mixture into a boil.
Lower heat and cover the wok. Continue cooking for 10 minutes.
Add oyster sauce and stir into the ingredients.
Add sayote and cook until sayote are soft.
Season with salt and pepper to taste.
serve and enjoy!