Pour the prepared tahini marinade over the chicken thighs, ensuring they are well coated.
Cover the dish or seal the bag and refrigerate for at least 30 minutes, or up to overnight, to allow the flavors to meld.
Preheat your grill to medium-high heat. If using a charcoal grill, wait until the coals are evenly hot and covered with ash.
Remove the marinated chicken from the refrigerator and let it sit at room temperature for 10-15 minutes.
Lightly oil the grill grates to prevent sticking.
Place the chicken thighs on the preheated grill and cook for 6-8 minutes per side, or until they are cooked through and have nice grill marks.
Use tongs to carefully flip the chicken halfway through the cooking time.
Check for doneness by inserting a meat thermometer into the thickest part of the chicken. It should register 165°F (75°C) when fully cooked.
Once cooked, transfer the grilled chicken to a serving platter and let it rest for a few minutes before serving.
Garnish the grilled chicken with additional lemon zest and chopped fresh herbs, if desired.
Serve hot alongside your favorite sides, such as rice, roasted vegetables, or a crisp green salad.