In a small pot, add water, soy sauce, rice vinegar, sugar and Chinese five spice powder. Bring to boil and simmer for 10 minutes.
Eggs
Half-fill a large pot with water and bring it to boil. Add a small pinch of salt.
Lower the eggs into boiling water carefully using a ladle and slow down the fire immediately. Simmer for 6 minutes (for softer texture) or 7 minutes (for harder texture). Stir the eggs in first two minutes.
Transfer the eggs out to cold water and gently peel the shells after cooled down. (If you feel it is quite hard to handle, place the eggs under small running water and peel the shells.)
Add soft boiled eggs in the marinating sauce, soaking for overnight (12-20 hours until well salted). Transfer them out when the eggs are well salted.