For the vermicelli noodles: In a medium pan, bring 2 quarts water to a boil. Add in the rice vermicelli noodle and stir to separate, then turn off and let it sit for 8 to 10 minutes.
Drain in a basket and rinse with cold water, separating the noodles so they don't stick together.
For the glazed pork: In a medium bowl, add the pork, onion head, yellow onion, fish sauce, sugar, black pepper and 6 ounces of the vegetable oil, and toss together. Let it sit in the fridge for about 2 hours.
Heat the pan over high heat and add the remaining 3 ounces vegetable oil. When the oil is nearly smoking, add the batches of pork and pan sear until medium golden brown, then turn the heat down to medium low, flip the pork over and let it simmer for 30 minutes.
For the chili-lime fish vinaigrette: In a small bowl, combine the fish sauce, sugar, white vinegar, lime juice, chili and 1 cup hot water and stir until the sugar dissolves. Let it sit for 20 minutes before serving.
Line 4 bowls with some chopped romaine lettuce, bean sprouts and sliced cucumber. Top with the cooked rice vermicelli noodle.
Place the cooked glazed pork on top of the noodle bowl and add the pickled carrots, daikon and crispy shallots. Drizzle the vinaigrette over the bowl and mix before serving.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.