1 pound brussels sprouts, rinsed, any older outer leaves discarded, stems trimmed slightly, sprouts sliced in half through the stem end
1 Tbsp peanut oil, or other vegetable oil
1/2 large onion, sliced thinly root to tip
2 teaspoons minced ginger
1 garlic clove, minced, about 1 teaspoon
1 Tbsp seasoned rice vinegar
2 teaspoons soy sauce
3 Tbsp hoisin sauce
1 teaspoon dark sesame oil
Salt to taste
Whisk together the seasoned rice vinegar, soy sauce, and hoisin sauce in a small bowl, set aside.
Place a steamer rack in a medium pot, add an inch of water. Heat the water to a boil, then add the brussels sprouts to the pot. Cover the pot and steam the brussels sprouts for 5 minutes. Remove the sprouts from the pot and lay them out on a baking sheet to cool while you cook the onions in the next step.
Heat the peanut oil in a wok or large sauté pan over high heat on your most powerful burner until the surface of the oil shimmers. Add the sliced onions and toss to coat with the oil. Sear over high heat until the edges of the onion slices begin to brown, about 4-5 minutes.
Add the ginger, garlic and brussels sprouts to the pan and toss to combine. Stir-fry for 2 minutes, or until the brussels sprouts begin to brown.
Add the rice vinegar, soy sauce and hoisin sauce mixture to the sprouts and toss to combine. Stir-fry for a minute or two (watch the sides of the pan and turn off the heat if you see any of the sauce scorch on the side of the pan). Drizzle with sesame oil and add salt to taste.