In a small bowl, cover the black beans (if using) with water, let soak for 30 minutes, and then drain.
Prepare a steamer in a wok or a large, lidded pot and bring the water to a boil over medium-high heat.
Meanwhile, using kitchen shears, cut off the gills and the fins (careful, sharp!) on the top, bottom, and sides of the fish. Run your fingers over the skin, especially near the gills and belly, toward the head to check for any last scales; remove the scales with the edge of a spoon or the back of a knife.
On both sides of the fish, make eight 2-inch-long parallel slits into the flesh, not quite deep enough to hit bone, starting about 1 inch from the gills. Place the fish in a pie plate. (The fish can hang over the edges so long as everything fits in the steamer. If not, cut the fish in half to fit and hope none of your guests are superstitious.) Tuck some of your chosen aromatics into each slit, then stuff the remaining aromatics in the cavity. Top the fish with the black beans.
Place the pie plate in the steamer, cover, and steam until the eyeball is opaque and the flesh of the fish is white and flaky at the thickest part near the head and first slit, 10 to 12 minutes.
While the fish is steaming, in a small heavy-bottom saucepan over low heat, slowly warm the oil.
When the fish is ready, remove it with the pie plate from the steamer. (Reassemble as a whole fish if you cut it in two.) Drizzle with the soy sauce, then top with the ginger and green onions. Turn the heat under the oil to high and warm until it just starts to smoke. Immediately pour the oil over the fish, getting as much of the ginger and green onions to sizzle as you can. Garnish with the cilantro and serve with a spoon big enough for drizzling the juices.
