Scale, gut, behead, remove tail from herring. Under running tap, rinse well, scraping out any kidney-stuff along backbone in body cavity. Pat dry with paper towel. Toss herring with a few pinches of salt, then arrange in steaming plate.
Grate up ginger (easier if it's frozen), about a ping-pong ball worth for the amount of herring in the picture. Slice up a generous clump of green onions.
Place plate in wok that has a an inch of so of water, a trivet is a good idea to keep it off the bottom of the wok. Steam for about 10 minutes, it will depend on the size of your fish (hint; try to use the same size herring).
Sautee ginger in a about 2 tablespoons of oil for a few minutes. Add in green onions, cook until softens/wilts but still has vivid green color. Add salt & pepper, plus whatever else might be handy like mirin, soy sauce, or balsamic vinegar. Drizzle this hot mixture over the steamed fish.