Wash the pork skins in a bowl of well-salted water 3 or 4 times. Drain well and set aside. Sprinkle the chilled pork with the Thai seasoning mixture, monosodium glutamate, salt and sugar and mix well with your hands until it feels sticky. Add the pork skins, mixing until well incorporated, then add the roasted rice powder. Roll the pork mixture into 10 slightly flattened balls. Wrap tightly in plastic wrap or banana leaves. Refrigerate for at least 3 days to ferment and cure.
For the rice balls:
Cook the onions in some oil in a large skillet over medium heat, stirring occasionally, until lightly browned, 10 to 12 minutes; transfer to a large bowl. Add the rice, cilantro and salt to taste. Mix in the eggs. Using lightly oiled or damp hands, firmly shape the rice into 30 slightly flattened balls. Pour 2 inches of oil into a wide heavy pot and heat over medium heat until a deep-fry thermometer registers 350 degrees F. Working in batches, fry the rice balls until golden and crispy. Transfer to a paper towel-lined plate or tray.
Crush the rice balls into chunks with the back of a large spoon in a large bowl. Season with fish sauce and lime juice. Break the som moo into pieces and add to the bowl along with cilantro, scallions, cucumbers, chiles and peanuts. Adjust the seasonings as needed. Transfer to a platter. Serve with lettuce leaves and mint leaves and eat as wraps.