In a bowl, whisk the miso paste, soy sauce, mirin, sake (if using), honey or brown sugar, grated ginger, and minced garlic together until smooth. This will be your flavorful glaze and marinade.

Pat the chicken thighs dry with paper towels. Place them in a shallow dish or a resealable bag. Pour about two-thirds of the miso glaze over the chicken, reserving the rest for later. Turn the thighs to coat evenly. Let them marinate for at least 30 minutes at room temperature or up to 4 hours in the fridge.

Preheat your oven to 400°F (200°C). Heat the oil in an oven-safe skillet over medium-high heat. Place the chicken thighs skin-side down in the hot skillet, cooking without moving them for 5-7 minutes until the skin is golden and crispy.

Flip the chicken thighs over, brush the tops with some of the reserved glaze, then transfer the skillet to the oven. Roast for 12-15 minutes, or until the chicken is fully cooked (internal temperature of 165°F or 74°C).

Take the skillet out of the oven and brush the chicken with the remaining glaze. For extra caramelization, you can broil the chicken for 1-2 minutes (watch carefully to avoid burning). Sprinkle with sliced green onions, sesame seeds, and fresh herbs if you like.

Serve your delicious miso-glazed chicken thighs hot with steamed rice and your favorite sautéed or roasted vegetables to soak up the tasty sauce!