Heat 1 tablespoon of cooking oil in a large pot over medium heat. Add the pork pieces and sear them until lightly browned on all sides, about 5–7 minutes. This step locks in the meat’s juices and enhances its flavour in the soup. Transfer the browned pork to a plate and set aside.

In the same pot, sauté the onions until translucent, about 2 minutes. Add the tomatoes and cook until softened and their juices are released. Stir occasionally to prevent burning.

Return the pork to the pot, then pour in the 6 cups of water. Bring the mixture to a boil, skimming off any foam that rises to the surface. Reduce to a simmer and cook for 20–30 minutes, or until the pork is tender.

Once the pork is tender, stir in the tamarind soup base mix or fresh tamarind pulp. If using fresh tamarind, boil the pulp in 1 cup of water, mash it, and strain to extract the juice. Adjust the sourness to your preference by adding more or less tamarind. Add fish sauce for additional depth of flavour.

Add the sliced radish and simmer for 5 minutes, or until it begins to soften. Follow with the eggplant and green chili peppers, if using. Continue cooking for another 5 minutes.

Add the long beans and cook for 2–3 minutes. Be careful not to overcook, as you want the vegetables to retain some crunch for texture contrast in the soup.

Finally, add the water spinach. Stir gently and let it cook for 1–2 minutes, just until wilted. Taste the soup and adjust the seasoning with additional fish sauce if needed.

Serve the Sinigang hot alongside steamed jasmine rice. For an authentic touch, offer fish sauce with sliced chili as a condiment. Garnish with fresh herbs like cilantro or more green chilies for a vibrant presentation. Encourage diners to enjoy the soup with its balance of sour, savoury, and fresh flavours.