Cut an onion in half, transfer to the oven, and bake for 10 - 15 minutes.
Remove the bottoms of scallions and the roots of coriander. Finely chop scallion and coriander. Mince garlic and shallots. Dice the white radish and carrot into bite-sized pieces. Peel the yam bean, wash it with water, and cut into thick slices.Slice the lemon into wedges and finely chop the chili pepper.Rinse the salted radish carefully with water to remove the excess salt. Cut it into short slices. Score the husk of the sugarcane stalk and chop it into sticks. Remove the stems of the shiitake mushrooms. Cut half of them into small pieces. For the rest, make two incisions in the shape of a cross on top of each with a sharp knife.
Chop the pork ham into medium-sized chunks. Debone the pork knuckles with a small sharp knife and fill them with pork ham.
Marinate the pig knuckles and the excess pork ham with 2 teaspoons of soup powder and 1 teaspoon of brown sugar in 15 minutes.
Tie each stuffed pig knuckle tightly with a kitchen twine.
Purify the pork ham, pork knuckles, pig trotters, and bones by boiling them in hot water with some salt and scallion for 3 - 4 minutes.
After that, put them in cold water immediately to prevent the meat from turning black.
In a skillet, roast dried shrimp lightly until they emit a meaty aroma.
Fill a stock pot with 4 liters of water. Add the meat, bones, yam bean, coriander root, sugarcane, salted radish, baked onions, roasted shrimp, and salt to the pot. Stew on medium heat for 1 hour to 1 hour 30 minutes. Constantly skim off foam to keep the broth clear.
Remove all the ingredients from the pot, except for the stuffed pork knuckles.
Add carrots and white radishes, then cook for 20 - 30 minutes on low heat. Season to taste.
Saute minced garlic and shallots in hot oil until they turn golden and fragrant. Set aside.
Saute the shiitake mushrooms in hot oil and possibly some water. Stir constantly for some minutes, then add them to the stock pot.
Add the bulbs of scallions and Vietnamese fish sauce to the broth.
Get the pork ham and stuffed pork knuckles out. When they cool down, cut the strings, then cut the pork into thin slices.
Parboil the thick noodles in hot water for 1 minute.
Add the noodles, pork, cooked pig trotters, and broth to your bowl. Garnish with fried shallots, scallions, chopped coriander, and black pepper.