Rinse the clear vermicelli with water, then soak it in a bowl with water.
Take the tofu puffs out of the package and rinse them under water to wash away any excess oil. Drain.
In a large pot, heat the oil and ginger over medium heat and sauté the ginger for a minute. Add the chicken stock and bring the broth to a boil.
Add the bok choy, tofu puffs, and carrots. When the soup comes back to a boil, lower the heat and simmer it for 5 minutes.
Drain the clear vermicelli and add them to the soup. Bring the soup back to a rapid simmer and cook for 1 minute or until the vermicelli has softened. Taste and adjust the seasoning with fish sauce and sugar. Turn off the heat and stir in the toasted sesame oil.