For the fresh lime juice, wash one lime thoroughly and cut off a piece lengthways to the right and left of the stem base. Core the sections and press out by hand. Discard the empty sections and the middle section (which contain bitter substances).
Wash the small, green chilli, cut crosswise into thin slices, leave the grains in place, discard the stem. Cap the garlic cloves at both ends, peel and squeeze with a garlic press.
Cut the fresh, washed and peeled roots, ginger and galangal across into very thin slices. Weigh and thaw frozen goods. Wash the fresh lemongrass, remove the hard stalk at the bottom, remove the brown and withered leaves and only use the white or light green parts. Cut this into thin slices. Remove the outer, green leaves if necessary. Weigh and thaw frozen goods. Wash the kaffir lime leaves and use them whole.
Put all the ingredients for the broth in a casserole with a lid and season with the fish sauce to taste. Let simmer for 45 minutes.
In the meantime, break the pasta into small pieces. Rinse the fresh and thawed prawns and dry them with paper towels. After about 40 minutes, add the pasta and celery leaves to the soup. Heat the sunflower oil in a pan and fry the prawns pink all over. Deglaze the soup with a little broth and add everything to the soup. Spread these on the serving bowls, serve hot and enjoy.