In a large mixing bowl, whisk together the Greek yogurt, olive oil, minced garlic, smoked paprika, cumin, coriander, lemon juice, salt, and black pepper until perfectly smooth.

Add the cubed chicken to the yogurt marinade, tossing well to ensure every piece is thoroughly coated. Cover the bowl and refrigerate for at least 30 minutes to tenderize the meat.

If using wooden skewers, soak them in water for at least 20 minutes to prevent them from catching fire. Thread the marinated chicken onto the skewers, alternating with pieces of red bell pepper and red onion.

Preheat your outdoor grill or an indoor grill pan over medium-high heat. Lightly brush the grates with a high-smoke-point oil to prevent the chicken from sticking.

Place the skewers on the hot grill and cook for 12 to 15 minutes, turning every 3 to 4 minutes. Cook until the chicken has a beautiful charred crust and reaches an internal temperature of 165°F (74°C).

Remove the smoky chicken skewers from the heat and let them rest for 3 to 5 minutes to lock in the juices. Serve warm on a platter alongside warm pita bread, fresh lemon wedges, and a generous bowl of tzatziki sauce.