In a bowl, combine 1/2 cup Greek yogurt, 2 tablespoons olive oil, 2 tablespoons fresh lemon juice, minced garlic, 1 teaspoon ground cumin, 1 teaspoon ground coriander, 1 teaspoon smoked paprika, 1 teaspoon kosher salt, 1 teaspoon ground black pepper and 1/4 teaspoon red pepper flakes (if using). Whisk until smooth.

Marinate

Add the chicken cubes to the marinade and toss to coat thoroughly. Cover and refrigerate at least 1 hour, ideally 4 hours, or up to overnight for best flavor. If short on time, marinate 30 minutes.

Vegetable Skewers

Prep vegetables

Cut bell peppers and onion into 1-inch pieces, halve zucchini into 1/2-inch rounds if needed, and rinse cherry tomatoes. Pat all vegetables dry to help them brown.

Season vegetables

Toss the cut vegetables with 1 tablespoon olive oil, 1/2 teaspoon kosher salt and 1/4 teaspoon ground black pepper in a bowl; set aside until skewering.

Assemble skewers

If using wooden skewers, soak them in water 30 minutes before assembling. Thread marinated chicken pieces and vegetables alternately onto skewers, leaving a little space between pieces for even heat circulation. Reserve any leftover marinade for basting (do not reuse marinade that touched raw chicken unless you boil it).

Grilling & Finishing

Preheat grill

Preheat a grill to medium-high (about 400°F / 200°C). Oil the grate lightly to prevent sticking.

Grill kebabs

Place skewers on the grill and cook 10–14 minutes, turning every 3–4 minutes for even char. Cook until chicken registers 165°F (74°C) in the thickest piece and vegetables are tender-crisp. If using a grill pan or oven broiler, cook similarly on a hot pan or under the broiler, turning once.

Rest and garnish

Transfer skewers to a platter and let rest 3–5 minutes. Sprinkle chopped parsley over the skewers and serve with lemon wedges and yogurt or tzatziki on the side for dipping.