Buy the tender coconut meat in the Asian shop. They are also available in bags sealed with coconut water or as young fruits. Cut the young fruit conically in the upper part and open one of the 3 eyes. Catch the coconut water in a bowl and filter it over a paper filter. Use a kitchen hatchet or cleaver to split the coconut in half and scrape out the tender coconut flesh. Thaw the prawns.
Wash the chillies and cut them crosswise into thin slices. Wash the kaffir lime leaves and use them whole. Wash the fresh lemongrass, remove the hard stalk at the bottom, remove the brown and withered leaves and only use the white to light green parts. Cut this into pieces approx. 8 cm long. Remove the outer, green leaves if necessary. Tap the bottom half of the pieces with the back of the knife. The stems should look oval, but remain intact.
Put the coconut water in a saucepan. If necessary, supplement with drinking coconut water. Mix in the coconut meat, kaffir lime leaves, lemongrass, lime juice, fish sauce and oyster sauce. Bring to a simmer and simmer for 10 minutes with the lid on. Stir every now and then.
In the meantime, rinse the thawed prawns. Cut into the back approx. 5 mm deep from the front to the end and remove the dark gray intestine if necessary. Wash the peppers, cap at the top, cut open lengthways on one side, fold open and core. Cut transversely into thin threads. Squeeze the garlic cloves.
Stir in the coconut milk, peppers and garlic and bring to simmer. Finally add the prawns and let them turn pink while stirring on reduced heat. Distribute the finished soup on soup bowls, garnish as desired, serve warm and enjoy.