Warm Chicken Shawarma Salad

Name: Warm Chicken Shawarma Salad
Ingredients: ¼ cup olive oil, divided; 1 ½ tablespoons shawarma seasoning, such as McCormick; 1 ½ pounds boneless, skinless chicken thighs (about 5 total); 1 red onion, cut into ½-in. wedges; ¾ cup (6 oz.) plain whole-milk Greek yogurt; ¼ cup chopped mint and/or parsley, plus leaves for serving; 3 tablespoons fresh lemon juice (from 2 lemons); ¾ teaspoon kosher salt, divided; 1 5-oz. container baby arugula; 2 cups grape tomatoes (about 10 oz.), halved; 2 6-in. pita rounds, quartered