1. Pat the boneless, skinless chicken thighs dry with paper towels. Place them in a shallow dish or a large resealable plastic bag.

2. In a medium bowl, combine the chopped fresh cilantro, fresh lime juice, olive oil, minced garlic, ground cumin, salt, black pepper, and optional red pepper flakes. Whisk everything together until well combined.

3. Pour the prepared marinade over the chicken thighs, ensuring each piece is thoroughly coated. If using a dish, turn the chicken a few times. If using a bag, massage the marinade into the chicken. Cover the dish or seal the bag and refrigerate for at least 30 minutes, or up to 2 hours for deeper flavor. Do not marinate for longer than 2 hours as the lime juice can start to “cook” the chicken.

4. If grilling, preheat your grill to medium-high heat (around 400 F). If baking, preheat your oven to 400 F (200 C) and line a baking sheet with parchment paper or foil for easy cleanup.

5. To grill: Place the marinated chicken thighs on the preheated grill. Cook for 6-8 minutes per side, or until the internal temperature reaches 165 F (74 C) with an instant-read thermometer.

6. To bake: Arrange the marinated chicken thighs in a single layer on the prepared baking sheet. Bake for 18-22 minutes, flipping halfway through, or until the internal temperature reaches 165 F (74 C).

7. Once cooked, remove the chicken from the grill or oven and let it rest for 5 minutes before slicing or serving. Garnish with extra fresh cilantro if desired.