Heat a cooking pot and pour-in the water. Bring to a boil.
Put-in the onions and tomatoes and cook until tender.
Put-in the tuna jaw and simmer for 15 minutes
Add the sinigang mix, chilies, and fish sauce then simmer for another 3 minutes.
Put-in the okra and string beans and cook for 3 minutes.
Add the eggplant and give additional 5 minutes to cook.
Mix-in the water spinach and simmer for a minute. Turn the heat off, cover the pot, and allow residual heat to completely cook the water spinach.
Transfer to a serving bowl and serve hot.
Share and enjoy!