Salt the pork ribs. In a large heavy bottomed pot, add a little oil just to coat. Once oil is hot, add the ribs and sear until browned on both sides; do not crowd the pot, you will probably need to do this in a couple of batches.

Once the pork is all seared, add them all back to the pot and add just enough water to cover the pork by about 1 cm. Add the fish sauce and simmer for about 15-20 minutes or until scum and foam has collected on top. Skim off the scum with a fine mesh strainer, then add onion and tomatoes, and simmer for another 45 minutes or until the pork is fork tender.

Meanwhile, if using tamarind pulp, use this time to make tamarind paste. Place the pulp in a medium bowl, cover with off-the-boil water and let sit until cool enough to handle. Squish the tamarind with your hands until all pulp has been released into the water. Strain off all the fibers.

Once the pork is fork tender, add taro cubes and chilies, and simmer for 7 minutes. Add the beans and cook for 2 more minutes, then add bok choy or any leafy greens you're using. Check that the taro is tender by piercing a fork through it and it should go through easily. Season the soup with most of the tamarind juice and then taste, adding more fish sauce and tamarind as needed (note: I used up all of my tamarind juice in the video). You shouldn't need any added sugar for this, but if the soup feels too sour, you can add a little sugar to balance.

Serve with jasmine rice!