Preheat oven to 450. Spray a baking sheet with cooking spray.
Grate 2 teaspoons of zest from the orange. Slice off ½ inch from each end of the orange and squeeze the juice into a medium pan. Add the zest to the pan and set aside.
Cut the orange in half and then into ¼ inch slices. In a large bowl, toss together the green beans, onion, olives, oil, wine, orange slices, salt and ¼ teaspoon of pepper. Spread it in an even layer on the baking sheet. Place the chicken in the bowl and toss with za'atar. Place on top of the green bean mixture.
Roast about 15 minutes or until chicken is no longer pink in the middle.
While it's roasting add the broth and ¼ teaspoon of black pepper to the orange juice in the pan. Bring to a boil. Stir in the couscous. Remove from heat and let sit covered for 5 minutes. Fluff with a fork.
To serve, divided the couscous among four plates and top with the green bean mixture and chicken tenders.