To prepare the fish, pat the fish dry with paper towels, including the belly cavity. Using a sharp knife, cut along both sides of the backbone from inside the fish without cutting through the skin.
To make the sauce, in a pot over low heat, combine the water, soy sauce, scallions, cilantro, ginger, shallot, and dried shrimp. Simmer gently for about 5 minutes until fragrant, then strain the sauce and set aside.
To prepare the fish for steaming, place the scallion stalks on a heatproof plate to create a rack and set the fish on top. Brush the fish lightly with cooking oil and place the ginger slices on top.
To steam the fish, bring water to a boil in a large steamer over high heat. Carefully place the fish inside, cover, and steam for about 6 minutes.
To finish the dish, remove the fish and pour off the steaming liquid. Discard the ginger and scallions used during steaming. Top the fish with the julienned scallions, ginger, and red bell pepper. Heat the cooking oil until smoking and carefully pour it over the aromatics. Drizzle the prepared sauce around the fish and serve immediately.