Preheat and prep the pan: Heat the oven to 425°F (220°C).
Line a large sheet pan with parchment or foil for easy cleanup. Lightly oil the surface.
Mix the sauce: In a bowl, whisk honey, soy sauce, minced garlic, vinegar, sesame oil, and red pepper flakes. If using cornstarch, whisk it in until smooth.
Season the chicken: Pat the chicken dry, then season both sides with salt and pepper.
Drying helps browning and keeps the texture juicy.
Toss the vegetables: In a separate bowl, toss the vegetables with olive oil, salt, and pepper. Spread them on the sheet pan, leaving space for the chicken.
Add the chicken to the pan: Nestle the chicken pieces among the vegetables, leaving a little room so everything roasts instead of steams.
Glaze generously: Spoon about two-thirds of the honey garlic sauce over the chicken. Drizzle a bit over the vegetables, but keep most of it on the chicken for best flavor.
Roast: Bake for 15 minutes.
Remove the pan, baste the chicken with any juices, and brush with more sauce. Toss the vegetables if needed for even browning.
Finish roasting: Return to the oven for 8–12 minutes, until the chicken reaches an internal temperature of 165°F (74°C) and the edges are caramelized. Total roast time is usually 23–27 minutes for thighs; breasts may cook faster.
Optional broil: For extra color, broil for 1–2 minutes at the end.
Watch closely to prevent burning.
Rest and serve: Let the chicken rest for 5 minutes. Sprinkle with green onions and sesame seeds. Serve with rice or your favorite grain, spooning pan juices on top.