Fill a steamer pot with water and heat on high heat until water is boiling.
Mix together the black bean sauce: sesame oil, black bean paste, ginger, xiaoxing wine, and sugar. Set aside.
Place fish filets on a small plate that can fit inside the steamer. Optional: add slices of silken tofu on the bottom of the plate. Then spread the sauce evenly onto the surface of the fish filets.
Place the plate of fish onto the steamer basket. Close the lid and steam 8-10 minutes depending on thickness of fish. Check the fish after about 8 minutes. Poke the fish lightly to see its juices. The fish is done with the juices run clear.