Make the marinade. In a bowl, whisk together olive oil, lemon zest, lemon juice, garlic, Dijon, oregano, thyme, salt, and pepper. It should smell like sunshine.
Marinate the chicken. Toss chicken thighs in half the marinade. Let sit 10–15 minutes while you prep the veggies.
Prep the veggies. In a large bowl, toss bell pepper, zucchini, onion, and tomatoes with the remaining marinade.
Build your sheet pan. Spread veggies onto your pan in an even layer. Nestle the chicken thighs over top, skin-side up.
Roast.
Bake at 425°F for 30 minutes.
Add olives + feta.
Scatter olives and feta over the pan. Roast another 10–15 minutes until the chicken reaches 165°F and the skin is golden.
Finish & serve. Top with fresh herbs and an extra squeeze of lemon. Serve straight from the pan or plate with rice, couscous, or warm pita.