To a soup pot add chicken stock, crushed garlic, ginger slices, spring onion, cilantro roots, black peppercorn. Let it come to a boil.
Gently slide the chicken breast to the pot. Simmer and let it cook for 8 minutes. Take the pot off the flame and let it rest for 5 minutes.
Remove the chicken breast, cover and keep it aside.
Strain the content of the pot in a colander. Discard the aromatics.
Transfer the strained stock back to the soup pot. Let it come to a boil, then simmer. Add soy sauce, Chinese cooking vinegar and sugar. Check the seasoning.
Time to add the veggies. If you are adding any tough veggies add them first let them cook for a few minutes or so, followed by softer vegetables. Veggies like spinach. bok choy should be added at the end and cook for 30 seconds.
Meanwhile, cook noodles in a separate pan. Shred chicken with two forks.