Prepare the marinade: In a bowl combine soy sauce, honey, sesame oil, cornflour, five spice and whole chicken breasts. Mix well and cover with cling wrap. Marinate 3 hours in the fridge.
Preheat oven to 180 degrees C and line a baking tray with aluminium foil. Place the chicken breasts on it and bake 30-40 minutes, basting with remaining marinade every 10 minutes.
Meanwhile, make the soup. Combine water and stock cube in a saucepan and heat to a simmer.
Add celery, spring onions, vinegar, soy sauce and sugar. Simmer while the chicken is cooking.
10 minutes before the chicken is done, cook the noodles according to packet directions. Add the bok choy to the soup.
Rinse the noodles with cold water and divide among 4 bowls. Remove the chicken from the oven and cut into thin strips. Place the chicken on top of the noodles. Ladle the soup over this and garnish with coriander.