01 - In a large mixing bowl, whisk together miso paste, soy sauce, mirin, honey, sesame oil, minced garlic, grated ginger, rice vinegar, and black pepper until completely smooth and well combined.
02 - Add chicken thighs to the bowl, turning each piece to ensure thorough coating with the marinade. Cover bowl and refrigerate for at least 30 minutes, or up to 4 hours for deeper flavor penetration.
03 - Preheat oven to 400°F. Line a baking tray with parchment paper or aluminum foil for easy cleanup.
04 - Remove chicken from marinade, allowing excess liquid to drip off. Place thighs on prepared baking tray in a single layer, ensuring pieces are not overcrowded.
05 - Roast chicken for 25 to 30 minutes, or until meat is fully cooked through and edges are nicely caramelized. Internal temperature should reach 165°F.
06 - Transfer cooked chicken to a serving platter. Sprinkle with toasted sesame seeds and finely sliced spring onions, if using. Serve immediately while hot.