1. Heat oven to 425°F (220°C). Pat chicken dry.
2. In a bowl whisk olive oil, lemon juice/zest, garlic, oregano, thyme, salt and pepper.
3. Toss potatoes and red onion with 1/3 of the marinade; spread on a rimmed sheet pan. Nestle chicken skin-side up and brush with remaining marinade. Roast 35–45 minutes until potatoes are tender and chicken skin is crisp and 175°F at the bone.
4. Add tomatoes for the last 10 minutes if using. Scatter olives and feta over the hot pan and rest 5 minutes.
5. Spoon the lemony pan juices over everything and shower with herbs.