Step 1
In a food processor, combine the garlic, basil, parsley, dill, and chives. Pulse until the herbs are finely minced. Add the Greek yogurt, mayonnaise, lemon juice, and 1/2 teaspoon of salt. Blend until a smooth and cohesive dressing forms.
Step 2
Place the chicken thighs in a large bowl and season them evenly with the remaining 1 1/2 teaspoons of salt. Pour in 1/2 cup of the prepared green goddess dressing, reserving the rest for serving. Toss gently to ensure each piece is well coated.
Step 3
Preheat the grill to medium-high heat for about 5 minutes. Clean and oil the grates thoroughly. Grill the chicken, turning once midway, until it develops a light char and is cooked through. The internal temperature should reach 165°F (74°C), which will take approximately 11 to 14 minutes.
Step 4
Transfer the cooked chicken to a serving platter and spoon the reserved dressing over the top before serving.
Step 5 (Make Ahead)
The green goddess dressing can be prepared up to one day in advance and stored in an airtight container in the refrigerator. The chicken may also be tossed with 1/2 cup of the dressing and refrigerated for up to 2 hours before grilling.