Combine the lemongrass in a mortar and pestle with salt and pound for 2 minutes until you've created a paste. Add the galangal and pound until smooth. Drain the chilies and add them to the paste with the shallots and shrimp paste. Pound each ingredient before moving on to the next. You should have around 1/2 cup of paste.
In a large pot or Dutch Oven over medium high heat cook the pork belly chunks. Let sear on all sides until browned and crispy. Discard rendered fat. Set cooked pork belly aside.
Heat the oil in the same pot over medium low heat until it shimmers. Add all of the paste, breaking it up with a wooden spoon and stirring occasionally, until it's fragrant, 2-3 minutes.
Stir in the shallots and cook until slightly softened, about 3 minutes, then add the curry powder and turmeric and stir frequently for a minute. Add the pork shoulder, stir to coat the pork, and cook for a few minutes.
Stir in the fish sauce, soy sauce, and brown sugar. Increase the heat slightly to bring the liquid to a simmer, cook until the sugar dissolves, then add the tamarind along with 2 cups of water. Increase the heat to high, let the liquid come to a strong simmer, then immediately decrease the heat to low and cover, cooking for 45 minutes.
Remove the lid and stir in the ginger and cook at a steady simmer until the pork shoulder is very tender, approximately 45 more minutes.
Stir in the pickled garlic cloves and chili, cook for 10 minutes then stir in the long beans, Thai basil and pork belly, cook until they're tender and slightly crunchy, about 5 minutes. Let the curry cool to warm and season with brown sugar or fish sauce to taste.
Serve in a large bowl topped with fried shallots.