Mix the Yogurt Marinade: Combine the yogurt, olive oil, minced garlic, lemon juice, ground cumin, smoked paprika, ground coriander, ground turmeric, cayenne pepper, kosher salt, and black pepper in a large mixing bowl. Whisk the mixture with a fork for 1 minute until all spices are fully incorporated and the marinade is a uniform orange-yellow color. The yogurt acts as a tenderizing agent because its lactic acid breaks down the surface proteins of the chicken, allowing the spices to penetrate deeper into the meat.
Marinate the Chicken: Add the chicken thigh cubes to the marinade bowl and toss with two spoons until every surface of each cube is coated. Press the chicken into the marinade, cover the bowl with plastic wrap, and refrigerate for 2 hours. A minimum of 2 hours allows the yogurt enzymes to tenderize the exterior without breaking down the texture of the meat. Do not marinate for longer than 8 hours, as extended acid exposure softens the chicken beyond the desired firm texture.
Prepare the Skewers: If using wooden skewers, submerge all 8 skewers in cold water for 30 minutes before threading to prevent charring during grilling. Remove the marinated chicken from the refrigerator and allow it to sit at room temperature for 15 minutes on a cutting board. Thread the chicken cubes onto the skewers, alternating each cube with a piece of red onion and bell pepper, and leave a 1cm / 0.4in gap between each piece. The gap between pieces ensures hot air circulates around all surfaces and each cube develops a crust rather than steaming against its neighbor.
Preheat the Grill: Heat an outdoor gas grill or grill pan over high heat for 10 minutes until the grill grates or pan surface reach 230°C / 450°F. Brush the grill grates with a folded paper towel dipped in 1 teaspoon of neutral oil, held with tongs, to prevent sticking. A properly preheated cooking surface creates the Maillard reaction on contact and produces the char marks characteristic of a well-grilled kebab.
Grill the Kebab Skewers: Place the assembled skewers on the preheated grill grates in a single layer, leaving 2cm / 0.8in of space between each skewer. Grill for 6 minutes on the first side without moving until the chicken develops deep char marks and lifts cleanly from the grates. Turn each skewer 180 degrees using tongs and grill for 6 minutes on the second side until the chicken is completely opaque, the edges are charred, and an instant-read thermometer inserted into the thickest cube reads 74°C / 165°F.
Rest and Serve: Transfer the cooked skewers to a clean cutting board or serving platter and rest for 5 minutes without covering. Resting allows the internal juices to redistribute from the center back toward the surface, so the first bite retains the moisture that accumulated during cooking. Serve immediately after the resting period with flatbread, a yogurt dipping sauce, or a simple tomato and cucumber salad.
