In a small bowl, mix together the za'atar seasoning, olive oil, minced garlic, lemon juice, salt, and black pepper to create a marinade.
Pat the chicken dry with paper towels, then place it on a large roasting pan. Rub the marinade all over the chicken, including under the skin for maximum flavor.
In the roasting pan, scatter the quartered onion, halved baby potatoes, and cherry tomatoes around the chicken. Drizzle a little olive oil over the vegetables and season with a pinch of salt and pepper.
Roast the chicken in the preheated oven for about 1 hour and 15 minutes, or until the internal temperature reaches 165°F (74°C) and the skin is golden brown and crispy. Baste the chicken halfway through cooking for extra juiciness.
Once cooked, remove the chicken from the oven and let it rest for 10-15 minutes before carving.
Garnish with fresh parsley and serve with the roasted vegetables on the side.
Notes
Baste the chicken halfway through cooking for extra juiciness.