Step 1

Combine black beans and garlic cloves on a cutting board and roughly chop them together.

Step 2

Rinse fish with cold running water and pat dry inside and out with paper towels. Sprinkle salt and white pepper all over fish, including inside cavity. Place 3 whole slices of ginger inside cavity.

Step 3

Set halved scallions on a heatproof plate large enough to hold the fish while small enough to fit inside steamer. Set fish directly on top of scallions so that the scallions mostly keep fish from making direct contact with plate.

Step 4

Set up a steamer and when it is ready, steam fish until cooked through, about 10 minutes. Carefully remove fish and plate from the steamer and pour off any accumulated juices into a bowl, then mix in soy sauce. Discard ginger slices from cavity of fish scallions from underneath. Transfer fish to a serving platter.

Step 5

In a wok or small saucepan, add chopped garlic and fermented black bean mixture, and cook over medium-high heat until garlic is soft, about 2 minutes. Add chili flakes, if using (and adding more if you want it spicier), remaining julienned scallions and ginger, cilantro, and the reserved fish-cooking liquid. Mix quickly and spoon everything on top of the fish. Serve immediately.