Mix salt, white pepper, MSG, Sichuan pepper, Shaoxing wine, soy sauce and peanut oil to make a sauce.
Rinse and dry the fish head and place in a bowl that will fit in your steamer. (If using a whole fish, place some of the ginger and scallions inside the fish.) Pour the sauce mixture over the fish head (and inside any crevices) and sprinkle the green and red chili peppers, scallions and ginger over it.
Bring water to a boil in a steamer. Carefully place the bowl on the steamer rack, cover and steam for 10-12 minutes, until fish is just done and flaky. Carefully remove the hot bowl and pour off most of the liquid. Serve the fish head along with its crown of chili peppers.