In a large pot, sear the pork shoulder cubes over medium-high heat until browned on all sides, using a splash of water if needed to prevent sticking.
Add the sliced onion and tomato wedges, sautéing for 3 minutes until the onion is translucent and the tomato begins to break down.
Pour in the water and bring to a gentle boil, then reduce heat and simmer for 20 minutes to tenderize the pork and develop the base flavors.
Stir in the tamarind paste and fish sauce, ensuring the paste is completely dissolved into the simmering broth.
Add the daikon radish and long beans, continuing to simmer for 6 minutes until the vegetables are tender-crisp.
Fold in the baby bok choy and season with sea salt and black pepper, cooking for 2 minutes until the greens are vibrant.
Ladle the hot soup into deep bowls, ensuring each portion has a balanced mix of pork and fresh vegetables.