Season the Protein: In a medium bowl, toss the chicken pieces with the dried oregano, smoked paprika, salt, and pepper until evenly coated.
Sear the Chicken: Heat the olive oil in a large skillet or wok over medium-high heat. Add the chicken in a single layer. Sear for 5–6 minutes, turning occasionally, until golden brown and cooked through. Remove the chicken from the pan and set aside on a plate.
Sauté the Vegetables: In the same pan, add the sliced peppers and broccoli. Stir fry for 3 minutes. Add the zucchini and red onions (if using), and cook for an additional 2–3 minutes until the vegetables are tender-crisp.
Combine & Aromatics: Return the cooked chicken and any juices to the pan. Stir in the garlic, halved cherry tomatoes, and Kalamata olives. Sauté for 2 more minutes until the garlic is fragrant and the tomatoes just begin to soften.
The Mediterranean Finish: Remove the pan from the heat. Squeeze the lemon juice over the mixture and sprinkle with lemon zest and fresh parsley.
Serve: Divide into bowls. Top with crumbled feta cheese if desired.