1️⃣ Marinate the Chicken
Whisk together the garlic, oregano, paprika, thyme, olive oil, salt, and pepper. Add the sliced chicken thighs and coat well. Marinate for at least 15–30 minutes, or up to 24 hours in the refrigerator.

2️⃣ Make the Tzatziki
Squeeze excess moisture from the grated cucumber using your hands or a clean kitchen towel. In a medium bowl, combine the cucumber, yogurt, lemon juice, olive oil, garlic, and salt. Stir well and refrigerate until ready to serve.

3️⃣ Preheat the Oven
Preheat your oven to 425°F (220°C). Line a large sheet pan with parchment paper or lightly grease it.

4️⃣ Season the Vegetables
Toss the onion, zucchini, and bell pepper with olive oil, oregano, garlic, salt, and pepper directly on the sheet pan. Spread into an even layer.

5️⃣ Add the Chicken
Scatter the marinated chicken strips evenly over the vegetables. Pour any remaining marinade over the top and squeeze fresh lemon juice over everything.

6️⃣ Roast
Bake for 20–25 minutes, until the chicken is cooked through and reaches an internal temperature of 165°F and the vegetables are tender with lightly caramelized edges.

7️⃣ Finish and Serve
Remove from the oven and immediately crumble feta over the top. Let rest for 2–3 minutes before serving. Spoon tzatziki generously alongside.

💡 Sheet Pan Tip: A standard 18 × 13-inch half-sheet pan gives you enough space for everything to roast in a single layer. If you’re doubling the recipe, use two pans rather than overcrowding one.