01 - Preheat the oven to 400°F (200°C).
02 - In a large mixing bowl, combine the grated ginger, minced garlic, tamari, honey, olive oil, rice vinegar, black pepper, sea salt, ground coriander, and red 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 surfaces evenly. Allow to marinate at room temperature for at least 15 minutes, or cover and refrigerate for 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 on top of the onion and lemon bed. Pour any remaining marinade over the chicken.
06 - Bake uncovered for 40 to 45 minutes, until the skin is golden brown and the internal temperature reaches 165°F (75°C) at the thickest part of the thigh.
07 - For an extra-crisp finish, switch the oven to broil on high for the final 2 to 3 minutes, watching carefully to prevent burning.
08 - Remove the dish from the oven and let the chicken rest for 5 minutes. Garnish with freshly chopped cilantro or parsley before serving.