Broiled Za'atar Chicken with Lemony Tahini

Tahini Sauce
2 In a small food processor, pulse [wprm-ingredient text="1 garlic clove" uid="1"], [wprm-ingredient text="½ cup Italian parsley leaves" uid="2"], [wprm-ingredient text="½ cup tahini paste" uid="3"], [wprm-ingredient text="¼ cup fresh lemon juice" uid="4"], [wprm-ingredient text="¼ cup cold water" uid="5"] and [wprm-ingredient text="1 teaspoon kosher salt" uid="6"]  or whisk in a bowl until smooth. Add more water if necessary to achieve a loose mayonnaise-like consistency. Taste and season with more salt to taste. The sauce keeps in the refrigerator up to 3 days ahead. 
Za'atar Chicken
5 Mix [wprm-ingredient text="Grated zest from 1 lemon" uid="8"], [wprm-ingredient text="2 tablespoons fresh lemon juice" uid="9"]. [wprm-ingredient text="2 tablespoons extra-virgin olive oil" uid="10"], [wprm-ingredient text="¼ cup chopped Italian parsley" uid="16"], [wprm-ingredient text="1 tablespoon za'atar seasoning, " uid="11"][wprm-ingredient text="1 finely chopped garlic clove" uid="12"], and [wprm-ingredient text="1 teaspoon kosher salt " uid="13"]in a large bowl. Add [wprm-ingredient text="1 ½ pounds boneless, skinless chicken" uid="14"] and toss to coat. Set aside to marinate 15-30 minutes or cover and refrigerate up to one day ahead.
12 Cook [wprm-ingredient text="1½ cups pearl couscous" uid="20"] in boiling, salted water according to package directions. Drain and toss with the chickpeas in a bowl.
6 Preheat a broiler to high, with an oven rack arranged closest to the heat source. Put the chicken on a foil-lined baking sheet. 
13 Broil the chicken 5-6 minutes per side, until the meat turns golden brown feels firm to the touch.  Let it rest about 10 minutes, then slice into ½-inch thick pieces
To serve
10 Spread some of the tahini sauce over the bottom of a large serving platter. Spoon the couscous mixture over the sauce. Arrange the sliced chicken on top and sprinkle with the remaining parsley leaves.  Serve warm or at room temperature, with additional sauce on the side.