1 Roast the onion halves cut side down in a large pan. Add the ginger and lemon grass. Wash the chicken, pat dry and add to the pan.
2 Cover the ingredients with 1.5 l water and bring to the boil. Reduce the heat and simmer for approx. 1.5 - 2 hours. Skim off the foam regularly.
3 Soften the noodles in cold water for approx. 30 minutes. Remove the chicken from the stock and let cool. Add the spices and the fish sauce to the stock and season with salt. Simmer for a further 60 minutes.
4 Remove the chicken meat from the bones, take off the skin and cut the meat into thin strips.
5 Bring salted water to the boil and cook the noodles for approx. 3 minutes. Strain the stock through a cloth.
6 Place the noodles, spring onions, carrots and meat in bowls and pour over the hot stock. Season with lemon juice, garnish with lemon zest and coriander and serve.