Prep the chicken: Trim excess fat and cut the chicken into 1.25–1.5 inch cubes for even cooking.
Make the marinade: In a large bowl, whisk yogurt, olive oil, garlic, lemon zest and juice, paprika (sweet and smoked), cumin, coriander, Aleppo pepper, oregano, salt, and black pepper.
Marinate: Add the chicken and toss to coat thoroughly.
Cover and refrigerate for at least 1 hour, ideally 4–8 hours. Overnight is even better for maximum tenderness.
Prep the grill or oven: Heat a grill or grill pan to medium-high. For oven cooking, preheat to 450°F (230°C) and set a rack in the upper third.
Line a sheet pan with foil and place a wire rack on top if available.
Skewer the chicken: Thread chicken onto skewers, alternating with chunks of red onion and bell pepper if you like. Don’t pack them too tightly; a little space helps them cook evenly.
Grill method: Oil the grates lightly. Grill the skewers for 10–12 minutes, turning every 2–3 minutes, until lightly charred and the internal temperature hits 165°F (74°C).
Rest for 3–5 minutes.
Oven method: Arrange skewers on the prepared rack. Roast 12–15 minutes, turning once halfway. For extra char, broil on high for the last 1–2 minutes.
Finish and serve: Sprinkle with chopped parsley and a squeeze of lemon.
Serve with flatbread, rice, salad, and a simple garlic-yogurt sauce if you like.