Add the ground pork and pork cartilage bones. Stir-fry until cooked through.

Add 4 1/4 cups (1 liter) water to the pork and curry paste. Add the cilantro roots and soaked red cotton tree flowers. Simmer over medium heat for 30–45 minutes, adding more water as needed if it reduces. Cook until the pork and flowers are tender—taste and check for your preferred softness.

While the pork is simmering, prepare the pork blood by cutting it into pieces and blanching in hot water once to reduce odor. Set aside.

Add the tomatoes, stirring occasionally, and simmer until the tomatoes are soft and starting to break down.

Add the pork meatballs. Once they are cooked, add the pork blood and simmer a bit longer. The soup is now ready.

To serve, ladle the hot Nam Ngiao soup over khanom jeen noodles. Top with chopped cilantro and green onions, fried garlic, and a squeeze of lime. Serve with pickled mustard greens on the side for extra flavor.