Pour the chicken stock into a large saucepan and cook over a low heat. Add the Chinese five spice, soy sauce and sesame oil and whisk together. Pour over 900ml(1½pt) boiling water and add the chilli. Bring to the boil and add the chicken breast strips. Simmer for 10 minutes.
Add the noodles and mushrooms and cook for a further few minutes. Then add the spinach and cook for 2-3 minutes more, until wilted. Cook until the chicken is cooked through with no pink showing.
Stir through the coriander and divide the soup between four deep bowls. Serve immediately with lime wedges on the side, if you like.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home.