Steam the fish, drain and put on plate. See this Cantonese Steamed Fish recipe for more details on how to cook your fish.
While the fish is steaming, prep the vegetables and have your pork ready for cooking. Mix 1 tablespoon water and cornstarch into a slurry mixture and set aside. Measure out shaoxing wine, bean sauce, hoisin sauce, sesame oil, sugar, and white pepper in a small bowl and set aside.
Heat wok to high and add 1 tablespoon of oil, garlic and onion. Stir for a minute and quickly add the rest of the vegetables and pork. Stir-fry for another minute. Add your prepared sauce and stir. Add your water and bring to a simmer.
Thicken the mixture with the cornstarch slurry until is coats a spoon. Add more water if it's too thick or more slurry if it's too thin. Stir in a teaspoon of oil to finish the sauce and pour the sauce over the steamed fish. Garnish with cilantro and scallion and serve immediately.