01 - In a large mixing bowl, whisk together the white miso paste, soy sauce, mirin, honey, sesame oil, minced garlic, grated ginger, rice vinegar, and black pepper. Continue whisking until the mixture forms a smooth, well-combined paste.
02 - Add the chicken thighs to the bowl with the marinade. Turn each piece thoroughly to ensure complete coating. Cover the bowl and refrigerate for at least 30 minutes. For enhanced flavor development, marinate up to 4 hours or overnight.
03 - Set your oven to 400°F. Line a baking tray with parchment paper or aluminum foil to facilitate easy cleanup.
04 - Remove the chicken from the marinade, allowing excess liquid to drip off. Place the thighs on the prepared baking sheet in a single layer, ensuring adequate space between pieces for proper heat circulation.
05 - Bake for 25 to 30 minutes, or until the chicken reaches an internal temperature of 165°F and develops caramelized edges. The meat should feel firm to the touch and the surface should appear golden-brown.
06 - Transfer the cooked chicken to a serving platter. Sprinkle with toasted sesame seeds and finely sliced spring onions if desired. Serve immediately while hot for optimal texture and flavor.