To prepare the prawns for this recipe, start by removing the head, shell, and antennae from the large ones and just the head, shell from the medium ones. Then, devein the prawns and rinse them thoroughly. This will help to ensure that the prawns are clean and ready to be added to the soup.
To infuse the base of the soup with aromatic flavors, add lemongrass, kaffir lime leaves, and galangal root to the pot of boiling chicken stock, along with a pinch of salt. Let the herbs boil for about 10 minutes to allow their flavors to fully infuse the broth.
Stir in some roasted Thai chili paste to add a spicy kick to the soup. If you’re not a fan of spicy food, add the paste in small increments and adjust to your taste preferences.