Wash the chicken breast and put it in a large pot. Peel and halve the onion. Heat a pan without fat and fry the onion halves with the cut surface facing down for 5-7 minutes. Take out and let cool down
Clean and wash the soup greens. Cut everything into large pieces. Remove the outer rind from the lemongrass, chop the inside roughly. Clean the chilli, cut lengthwise, wash and remove the seeds. Cut the pod into small pieces. Add the onion, soup vegetables, lemon grass and chilli to the pot. Add 1 1/2 litres of cold water so that the meat is covered. Salt a little, bring everything to the boil and simmer gently over a low heat for about 1 hour. Remove any foam that develops in between with a skimmer
In the meantime, put glass noodles in a bowl, pour boiling water over them and let them stand for 2-3 minutes. Pour the noodles onto a sieve, rinse with cold water and place in a bowl of cold water
Clean and wash the sugar snap peas and cut them diagonally into large pieces. Quarter the peppers, clean, wash and cut into very fine strips. Clean, wash and quarter the mushrooms
Lift the chicken breast out of the broth and pour the broth through a fine sieve into a pot. Let the chicken breast cool down a little. Remove the skin and remove the meat from the bones. Pluck the chicken meat into pieces
Add sugar snap peas, mushrooms and peppers to the soup, bring to the boil and simmer for about 5 minutes. Drain the glass noodles. Add noodles and chicken meat to the hot broth. Heat up again and season with salt and a little pepper
Wash the coriander, shake dry and pluck off the leaves. Arrange the soup in deep bowls and sprinkle with coriander leaves