1. Preheat the oven to 400°F. Cut the ends off the brussels sprouts and remove the outer leaves. Cut the brussel sprouts in half lengthwise. Add the sprouts to a bowl with the peanut oil, salt, and pepper and toss to coat. Place the sprouts in a single layer on a rimmed baking sheet and roast in the preheated oven until lightly browned, about 15 minutes. Transfer the sprouts to a large bowl and set aside.

2. Add the soy sauce, sesame oil, vinegar, honey, garlic, and red pepper flakes in a bowl to a wok or saucepan over medium heat. Stir and bring to a boil then reduce heat to medium-low.

3. In a small bowl combine the water and cornstarch until cornstarch is fully dissolved. Stir the cornstarch mixture into the sauce and continue to cook until sauce is thickened, about 3 minutes.

4. Pour the sauce into the bowl with the brussels sprouts and sprinkle on the peanuts and green onion. Toss to combine and serve over steamed rice.