Preheat the oven to 425°F (220°C). Toss the halved Brussels sprouts with 1 tablespoon olive oil, salt, and pepper. Spread them in a single layer on the prepared baking sheet, cut side down. Roast for 20-25 minutes, until golden brown and crispy.
While the sprouts are roasting, heat the remaining 1 tablespoon of oil in a large skillet over medium heat. Add the dried red chili peppers, minced garlic, ginger, and white parts of the green onions. Sauté for 1-2 minutes until fragrant.
Stir in the Tamari sauce, rice vinegar, keto brown sugar, and sesame oil. Simmer for 2-3 minutes. If using xanthan gum, whisk it in now to thicken the sauce. Remove from heat and set aside until Brussel sprouts are done roasting. If the sauce thickens too much while cooling, whisk in 1 to 2 tablespoon water to thin the glaze.
Add the roasted Brussels sprouts to the skillet and toss to coat them evenly in the sauce. Cook for 1-2 minutes until the sprouts are glazed and slightly caramelized.
Transfer to a serving dish, garnish with the green onion tops and roasted peanuts. Serve hot and enjoy!