01 - Preheat the grill or grill pan to medium-high heat.
02 - In a large bowl, combine ground beef, grated onion, minced garlic, parsley, cilantro, cumin, coriander, cinnamon, paprika, chili flakes, salt, and black pepper. Mix gently until just combined, avoiding overworking the meat.
03 - With slightly damp hands, divide the mixture into 8 equal portions. Shape each portion into an oval or sausage shape around a metal or soaked wooden skewer, pressing firmly to ensure adherence.
04 - Grill the kebabs for 10 to 12 minutes, turning occasionally, until they are browned and cooked through.
05 - While the kebabs cook, whisk together Greek yogurt, minced garlic, chopped mint, lemon juice, olive oil, salt, and pepper in a small bowl. Refrigerate until serving.
06 - Serve the kebabs hot, drizzled with yogurt sauce and accompanied by warm flatbreads, sliced red onion, and fresh herbs if desired.