Prepare the following, adding each to the same large bowl as you complete it: Halve 1 Persian or ½ English cucumber lengthwise, then cut crosswise into ½-inch pieces (about ¾ cup). Halve ½ cup cherry or grape tomatoes. Halve and thinly slice 1 small red onion (about ½ cup); place half in the bowl and reserve half for the chicken. Halve 1 medium romaine lettuce heart lengthwise, then cut crosswise into ¼-inch-thick strips (about 4 cups).

Grate 1 garlic clove into a small bowl. Add ½ cup plain Greek yogurt, 2 tablespoons brine from pickled banana peppers or pepperoncini, 2 tablespoons of the water, and 1 tablespoon tahini. Stir to combine. Taste and season with kosher salt and black pepper as needed. Pick the leaves and tender stems from 6 fresh parsley sprigs and finely chop (about 2 tablespoons).

Heat 3 tablespoons of the olive oil in a large skillet over medium-high heat until shimmering. Add 2 cups shredded, cooked chicken, reserved onions, and 2 tablespoons shawarma spice blend. Toss to coat and spread the chicken out into an even layer. Cook, stirring occasionally, until golden-brown and crispy in spots, about 5 minutes.

Add the remaining 2 tablespoons water and scrape up any browned bits from the bottom of the pan. Transfer to a plate.

Heat the remaining 1 tablespoon olive oil in the same pan. Tear 1 pita bread into 1 ½-inch pieces and add to the pan. Toss to coat and cook, flipping the pieces occasionally, until toasted and golden-brown, 3 to 5 minutes.

Add the dressing to the bowl of vegetables and toss to coat. Drain ¼ cup pickled banana peppers or pepperoncini, then sprinkle over the salad. Top with the chicken shawarma and pita chips. Crumble 3 ounces feta cheese (about ⅓ cup) over the salad. Sprinkle with the parsley and serve.