Start by boiling the pork and removing the scum as it floats to the top. Water level should be just past the meat. Too much water will make the broth bland - if you find the level getting too low, just add more.
Once all the scum has been removed, put in the onion, tomatoes, salt, and pepper. Bring to a boil and simmer under medium/low heat for 30-45 minutes or when the meat is fork tender.
When meat is tender, add gabi (taro) and bring to a boil until soft.
Now it's time for the best part - put in half of the tamarind soup base packet, stir, then taste. Not enough tang? Add more!
As for the final step, put in the water spinach. Stir, cover, and turn off heat. Let sit for 1-2 minutes before serving.