In a large bowl, combine the ground beef or lamb, grated onion, minced garlic, parsley, cumin, coriander, cinnamon, salt, black pepper, cayenne pepper, and olive oil. Mix until well combined.
Divide the mixture into 8 equal portions and mold each portion around a skewer, shaping it into a long, flat kebab.
Preheat your grill or grill pan over medium-high heat. Cook the kafta kebabs for about 4-5 minutes on each side, or until they are cooked through and have nice grill marks.
While the kebabs are cooking, prepare the tzatziki sauce by mixing the Greek yogurt, grated cucumber, minced garlic, dill, lemon juice, salt, and pepper in a bowl. Adjust seasoning to taste.
Serve the kafta kebabs hot with the tzatziki sauce on the side.