In a mixing bowl, whisk together the soy sauce, pure maple syrup, rice vinegar, minced garlic, grated ginger, and sesame oil until well combined. Sprinkle in freshly ground black pepper and red pepper flakes if desired.

Place the chicken thighs in a large resealable bag or a bowl, then pour the marinade over the chicken, ensuring each piece is well-coated. Cover and refrigerate for at least 1 hour, preferably overnight.

Preheat your oven to 400°F (200°C). This helps achieve crispy skin.

Prepare your baking dish by lining it with parchment paper or lightly greasing it.

Once preheated, place the marinated chicken thighs skin-side up in the dish and bake for 25–30 minutes, until golden brown and the internal temperature reaches 165°F (75°C).

In the final 5 minutes, switch to broil to intensify the glaze and crisp the skin. Keep a close watch to avoid burning.

Remove from the oven and let the chicken rest for 5 minutes. Garnish with sesame seeds and green onions before serving.