Make the marinade: in a large bowl or a large freezer bag whisk together 10 minced garlic cloves, harissa paste, 1/4 cup olive oil, 2 tablespoons lemon juice, balsamic vinegar, 1 tablespoon ground cumin, 1 tablespoon ground coriander, 2 teaspoons smoked paprika, 2 teaspoons ground cardamom, 2 teaspoons salt, 1 teaspoon onion powder, 1 teaspoon black pepper, and 1/4 teaspoon ground cinnamon.
Add the pounded chicken thighs to the marinade and turn to coat thoroughly. Seal or cover and refrigerate for at least 4 hours and up to 24 hours. Remove from the refrigerator 20–30 minutes before cooking to come to room temperature.
Make the yogurt sauce: place 1 cup Greek yogurt, 1/3 cup packed cilantro, 1/3 cup packed parsley, 2 peeled garlic cloves, 2 tablespoons lemon juice, 1/2 teaspoon ground cumin, 1/2 teaspoon salt, and 1/4 teaspoon black pepper in a blender and blend until the herbs are chopped and the sauce is smooth. For a thicker sauce stir in extra yogurt instead of blending.
To grill: preheat a grill to medium (about 400–450°F). Grill the chicken, covered, 5–7 minutes per side until an instant-read thermometer registers 170°F. Transfer to a cutting board and rest 5 minutes before slicing.
To pan-cook: heat 1 tablespoon vegetable oil in a large cast-iron skillet or grill pan over medium-high. Cook chicken in a single layer in batches 4–5 minutes per side; after flipping, cover and reduce heat to medium and cook 3–5 more minutes until the center reaches 170°F. Rest 5 minutes before slicing.
To bake (optional): line a baking sheet with foil and spray with cooking spray. Arrange chicken in a single layer and bake at 425°F for 20–25 minutes until internal temperature reaches 175°F. Rest 5 minutes before slicing.
Serve sliced chicken with the chilled yogurt-herb sauce.
