For the black bean sauce: Soak the beans in cold water for a few minutes to remove the salt. Drain the beans and pour the rice wine over them; use a fork or the back of a spoon to mash them up.
Heat the oil in a wok over high heat. Add the garlic, ginger and chili and stir-fry briefly until just beginning to brown and catch on the wok. Add the mashed beans, stir briefly, and then add the stock, soy sauce and white pepper. Bring the mixture to a boil, stirring, and cook briefly to thicken. Add the cornstarch slurry and cook until the sauce thickens and is glistening. Remove from the heat and keep warm until ready to serve.
To prepare the fish, filet the flesh, keeping the skeleton whole with the head intact. Cut the fish into 2-inch cubes. Mix the potato starch, salt, and white pepper together and lightly dust some over the fish skeleton and head. Toss the fish pieces in the remaining starch mixture until well coated, shaking off the excess. Heat the deep fryer or a wok with about 3 inches of oil to 350 degrees F. Using two metal skewers, pierce the skeleton body with them in two spots to secure the skeleton standing upright and slightly curved. Gently lower the skeleton into the oil and fry briefly on both sides until light golden. Drain on paper towels and set aside.
When ready to serve, fry the fish pieces very quickly, until cooked through and just beginning to turn light golden, 1 to 2 minutes.
Arrange the fish body, standing upright on a serving platter and pile the fish pieces in the center. Garnish with the edible flowers and scallions.
Pour some black rice vinegar over the ginger in a small bowl. Serve the fish with the black bean sauce and ginger vinegar on the side.