Preheat the oven to 425°F.
Place the cauliflower and bell pepper strips on a baking sheet. Drizzle with olive oil and toss to coat. Sprinkle with a pinch of salt and freshly ground pepper.
Roast for 15 minutes, until the cauliflower is just slightly crisp and the peppers are beginning to soften. While the vegetables roast, whisk together the soy sauce, hoisin, rice vinegar, sesame oil, maple syrup, cornstarch, garlic, and ginger in a bowl. Whisk until smooth and no cornstarch lumps remain. After 15 minutes, remove the pan from the oven. Add the chiles de arbol and pour the sauce over the cauliflower and peppers. Toss well to coat. Return the pan to the oven and roast for another 15 to 20 minutes, stirring every 5 to 10 minutes, until everything is glazed and caramelized.
Once done, remove from the oven. Sprinkle with green onions, chopped peanuts, and toasted sesame seeds. Serve hot as a side dish or over rice. Enjoy!