In a large mixing bowl, combine the lean ground beef, chopped onion, minced garlic, and chopped cilantro. Add ground cumin, ground coriander, paprika, salt, and pepper. Mix well until the mixture is sticky and evenly distributed, about 3-4 minutes.

With wet hands, form the beef mixture into oval-shaped patties or skewers, about 1 inch thick. Place the koftas on a clean plate and rest them while preheating the grill.

Preheat the grill to medium-high heat, about 400°F, and lightly grease the grates to prevent sticking.

Grill each side of the koftas for about 5 minutes until a golden-brown crust forms and the internal temperature reaches 160°F.

In a separate bowl, mix the Greek yogurt with fresh lemon juice and chopped dill or mint. Season with salt and pepper to taste, then let the sauce rest for 10 minutes.

Let the beef koftas rest for a couple of minutes off the heat, then serve with the yogurt sauce and optional sides.