Step 1: Pat the chicken thighs thoroughly dry with paper towels to ensure crispy skin. Trim any excess skin or fat if desired, then place the dried chicken thighs in a large bowl or resealable bag.
Step 2: In a small bowl, whisk together the olive oil, minced garlic, lemon zest, fresh lemon juice, chopped fresh rosemary, chopped fresh thyme, dried oregano, sea salt, and black pepper. If using, add a pinch of red pepper flakes.
Step 3: Pour the marinade over the chicken thighs, ensuring each piece is thoroughly coated. Massage the marinade into the chicken. Let marinate for at least 30 minutes at room temperature, or for 2-4 hours (or overnight) in the refrigerator. Bring to room temperature for 15-20 minutes before cooking if refrigerated.
Step 4: Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper or foil, or use a wire rack set over a baking sheet for ultimate crispiness.
Step 5: Arrange the marinated chicken thighs on the prepared baking sheet in a single layer, skin-side up, making sure there's space between each piece for air circulation. Place lemon slices and extra herb sprigs around the chicken if desired.
Step 6: Bake for 35-40 minutes, or until the internal temperature of the thickest part of the thigh reaches 175°F (80°C) and the skin is deeply golden and crispy. For an extra crispy finish, broil for the last 2-3 minutes, watching carefully to prevent burning.
Step 7: Remove from the oven and let the chicken thighs rest on the baking sheet for 5-10 minutes before serving. This allows the juices to redistribute, keeping the chicken tender and moist.