Step 1: Using a mortar and pestle, grind together the garlic, ginger, chillies, 1 thumbnail-sized portion of shrimp paste and mixed peppercorns until a smooth paste is formed. Set aside. Step 2: In a bowl, combine the chicken stock, oyster sauce and kecap manis. Set aside. Step 3: Add a dash of cooking oil and over a low heat. Fry the prawns for around 3 minutes on each side until they turn orange. Remove and drain on a paper towel. Step 4: When all the prawns are cooked, drain the oil out of the wok, leaving around 2 tablespoons remaining. Step 5: Add the paste and the spring onions and cook for around 2 minutes until fragrant. Step 6: Add in the stock mixture and bring to the boil. Step 7: Once boiling, add the butter and stir until melted. Step 8: Add the prawns to the wok and cook for a further 2 minutes. Serve with fresh coriander.