Preheat oven to 400°. Whisk together the first 8 ingredients. Set aside., Sprinkle both sides of chicken with salt and pepper. Place chicken and sweet potato in a single layer in a foil-lined 15x10x1-in. baking pan. Drizzle with 1 tablespoon olive oil and a third of the hoisin mixture; toss to coat., Bake 15 minutes; turn chicken and potatoes. Add cauliflower and red pepper; drizzle with another third of the hoisin mixture and remaining olive oil. Bake until a thermometer inserted in chicken reads 170°-175°, about 25 minutes longer. Drizzle with the remaining hoisin mixture. If desired, sprinkle with sesame seeds.