01 - Combine ground beef, grated onion, minced garlic, chopped parsley, cilantro, cumin, coriander, paprika, cinnamon, allspice, chili flakes, salt, and black pepper in a large bowl. Add egg if using for extra binding.
02 - Mix thoroughly with hands until all ingredients are well incorporated and the mixture becomes slightly sticky, ensuring even distribution of spices throughout the meat.
03 - Divide mixture into 8 equal portions. Shape each portion around metal or soaked wooden skewers into long, oval-shaped kebabs, pressing firmly to ensure they hold their shape during cooking.
04 - Preheat grill or grill pan over medium-high heat. Lightly oil the grates or pan to prevent sticking.
05 - Grill kebabs for 10 to 15 minutes, turning occasionally, until nicely browned on all sides and cooked through to an internal temperature of 160°F.
06 - Remove from heat and let rest for 3 to 5 minutes to allow juices to redistribute. Serve hot with lemon wedges, flatbreads, and fresh vegetable accompaniments.