Cut the pork into bite-sized pieces. Whisk the thin coconut milk and shrimp paste together in a bowl. Pour into a large pot with the onion, ginger, and pork; bring the mixture to a boil, reduce the heat to medium-low, and simmer for 5 minutes.
Add the green beans, calabash, and green chile pepper; cover again and continue cooking until the mixture is nearly dry, about 10 minutes. Stir the thick coconut milk into the mixture. Add the prawns; reduce heat to medium, cover, and cook until nearly all the moisture is absorbed and prawns are pink, about 5 minutes. Serve hot.