01 - Preheat oven to 400°F (200°C).
02 - In a large mixing bowl, combine grated ginger, minced garlic, tamari, honey, olive oil, rice vinegar, black pepper, salt, coriander, and chili flakes. Whisk until well blended.
03 - Pat the chicken thighs dry with paper towels. Add them to the marinade and toss thoroughly to coat all pieces evenly. Allow to marinate for at least 15 minutes at room temperature, or cover and refrigerate up to 4 hours for deeper flavor penetration.
04 - Arrange the sliced onions and lemon slices in an even layer across the bottom of a 9x13-inch baking dish.
05 - Place the marinated chicken thighs skin-side up over the onion and lemon bed. Pour any remaining marinade from the bowl evenly over the top.
06 - Bake uncovered for 40 to 45 minutes, until the skin is golden brown and juices run clear. The internal temperature of the thickest part should register 165°F (75°C).
07 - For extra-crispy skin, switch the oven to broil on high for the final 2 to 3 minutes, watching closely to prevent burning.
08 - Remove from the oven and let the chicken rest for 5 minutes. Garnish with freshly chopped cilantro or parsley before serving.