Preheat oven to 220°C (or 200°C fan bake). Bring a large pot of salted water to the boil.
Prep ginger and garlic. In a small bowl, combine soup spices together. Pat chicken dry, season with salt and toss with ginger, garlic, ⅔ of soup spices and oil. Prep carrot and bok choy. Heat oil in a large pot or deep fry-pan on medium-high heat and cook chicken for about 3 minutes each side, until golden.
Add carrot, stock and fish sauce to pot with chicken, bring to a simmer, reduce heat to low and cook for about 10 minutes. Remove chicken from soup and set aside to rest. Add bok choy to soup and simmer for a further 3 minutes, until just tender.
While chicken cooks, toss corn, sesame oil and remaining soup spiced on a lined oven tray and roast for about 10 minutes, until golden.
Use hands to separate noodles. Place noodles in pot of boiling water, stir to separate strands and cook for 5 minutes, until just tender. Drain, refresh under cold water and leave to drain again. Drizzle with oil to prevent sticking. Roughly pull apart chicken with two forks (or roughly chop) and return to soup along with any resting juices. Cook, stirring for 1 minute, until chicken is hot through. Season to taste with soy sauce.
Serve noodles and soup topped with corn.