Prepare one whole free-range chicken (use half if serving fewer people), wash it thoroughly, and cut into small pieces for later use. Slice ginger and soak vermicelli in water until soft. Heat a small amount of oil in a pan (since the chicken will release its own fat, a minimal amount is sufficient) and sauté the ginger slices until fragrant. Add the chicken pieces and stir-fry until they begin to change color.
Pour in half a tablespoon of soy sauce and stir evenly (as Grandmother says, a little soy sauce is enough to add color and aroma). Add an adequate amount of water, bring to a boil over high heat, then reduce to a low simmer. Cook slowly until the chicken broth is fully developed (the longer the cooking time, the richer the broth). This step can be transferred to a stew pot or clay pot. Before serving, add the soaked vermicelli, season with an appropriate amount of salt, and bring to a boil over high heat. Turn off the heat and serve directly at the table.