In a large bowl, whisk together yogurt, olive oil, lemon juice, minced garlic, ground cumin, ground coriander, paprika, sumac (if using), black pepper, kosher salt and cinnamon. Taste and adjust salt or lemon as needed.

Marinate

Add the meat cubes to the marinade and toss until fully coated. Cover and refrigerate for at least 2 hours, preferably 4–8 hours. For best flavor with lamb, marinate up to overnight. If short on time, a minimum 30 minutes will still add flavor.

Skewers & Finish

Prepare skewers and vegetables

If using wooden skewers, soak them in water for 30 minutes to prevent burning. Cut onion and bell pepper into pieces similar in size to the meat cubes. Drain excess marinade from the meat (reserve any excess to baste if desired).

Assemble skewers

Thread meat cubes onto skewers, leaving a little space between pieces for heat circulation. Optionally alternate with onion and bell pepper pieces. Do not overcrowd; plan on about 6–8 meat cubes per skewer depending on size.

Preheat grill or broiler

Preheat a charcoal or gas grill to medium‑high (about 425–475°F / 220–245°C). If broiling indoors, position the oven rack 4–6 inches from the broiler and preheat on high. Oil the grill grates lightly or brush the skewers with a little neutral oil to prevent sticking.

Cook skewers

Place skewers on the hot grill or under the broiler. Cook for 10–14 minutes, turning every 2–3 minutes so all sides char and cook evenly. Chicken should reach an internal temperature of 165°F (74°C); lamb is best at 145–160°F (63–71°C) depending on desired doneness. If using thicker cubes, allow a few extra minutes.

Rest and garnish

Remove skewers from heat and let rest for 5 minutes. Sprinkle chopped parsley or cilantro over the skewers and serve with lemon wedges for squeezing.

Serve suggestions: Serve over rice, with flatbread (pita), tzatziki or garlic sauce, and a simple salad of cucumber and tomato if desired.