Slit the prawns lengthwise through the shell and remove the entrails. Rinse well, drain and set aside in a plastic colander.
Combine mashed fermented black beans with sugar and sesame oil. Heat one teaspoon oil and sesame oil in a small saucepan. Fry garlic and ginger until fragrant. Add black bean mixture and a splash of cooking wine (optional). Dish out and set aside.
Arrange the prawns in a deep heat-proof dish and pour the prefried black bean mixture over. Add the chopped chilli, bird´s eye chillies and pepper. Steam for 5-6 minutes. Remove, garnish with chopped coriander leaves and serve immediately.