Fry the ginger and galangal (1 tbsp set aside), the prawn shells, 2 chili peppers and the garlic in hot oil for 2-3 minutes.
Quench with 800 ml water.
Add the lime leaves and the lemongrass and simmer for approx. 20 minutes.
Sieve and season with fish sauce and lime juice.
Add the prawns, the remaining ginger and chili peppers and cook on a low heat for around 3 minutes.
Serve garnished with fresh herbs.