Bring 2 cups of water to a rolling boil in a medium saucepan. Add the quick-cooking barley and cook according to package directions, typically 10-12 minutes until tender. Set aside and keep warm.

While the barley cooks, heat 2 teaspoons of olive oil in a large skillet or wok over medium-high heat. Add the cubed chicken and stir-fry for 6-7 minutes, stirring frequently, until the pieces are golden on the outside and the internal temperature reaches 165°F with no pink remaining. Transfer chicken to a clean plate and keep warm.

Add the remaining 1 teaspoon of oil to the same skillet. Toss in the chopped onion and stir-fry for about 3 minutes until it becomes translucent (you should be able to see through the edges) and fragrant.

Add the zucchini, minced garlic, oregano, basil, salt, pepper, and red pepper flakes to the skillet. Stir-fry for 2-4 minutes, stirring constantly, until the zucchini is crisp-tender (still has a slight bite but not raw-tasting). Avoid overcooking to maintain texture and bright green color.

Return the cooked chicken to the skillet along with the chopped tomatoes, olives, and fresh parsley. Stir everything together gently and cook for 1-2 minutes until heated through and the flavors meld beautifully. Taste and adjust salt if needed.

Serve the chicken mixture over the cooked barley, using approximately 1 cup of the stir-fry with 3/4 cup of barley per serving. Let rest for 2-3 minutes before serving. Garnish with extra parsley if desired.