Chop the chicken bones into pieces and rinse with salt. Blanch them in boiling water with 2 tablespoons vinegar for 5 minutes, then rinse again. Place the bones in a pot with 5 liters (about 5.3 quarts) of cold water, 5 shallots, 1-2 onions, 1 piece of ginger (all roasted until golden), 1 teaspoon salt, 1 teaspoon MSG, and 15 grams (1/2 oz) rock sugar. Add the chicken meat to the pot and bring to a boil. Once boiling, reduce the heat and skim off any foam to keep the broth clear.

While boiling the chicken, prepare: 2 cups shrimp shells (roast until golden), 7 cilantro roots (use the whole sprig), and 1 daikon radish (cut into thick slices). Place the shrimp shells, onions, and shallots in mesh bags and add to the broth. Simmer gently for about 25 minutes, then turn off the heat and cover the pot to let it rest for 10 minutes. Remove the chicken and immediately place it in a bowl of ice water for a few minutes to keep the skin firm and the meat juicy.

Continue simmering the broth for another 30 minutes to extract more flavor from the chicken bones. Meanwhile, slice the green onion roots into thin strips, thinly slice the onion, chop the cilantro, and cut the kaffir lime leaves into thin strips. Remove the bones, onions, shallots, ginger, shrimp shells, daikon, and cilantro roots from the broth. Strain the broth to remove any residue. Season the broth with 1 tablespoon fish sauce. Shred the chicken meat to prepare for serving.

Blanch 5.3 oz (150 grams) of rice noodles per bowl in hot water (about 176°F/80°C) for about 20 seconds. Place the noodles in a bowl, top with shredded chicken, and ladle hot broth over until the noodles are just covered. For kids, just add some thinly sliced onion, chopped green onion, and cilantro. For adults, add all the toppings: thinly sliced onion, shredded green onion, thinly sliced kaffir lime leaves, cilantro, and sliced chili. Sprinkle with a little black pepper and enjoy with a small dish of Northern-style chili sauce if desired.