In a large mixing bowl, gently combine the ground lamb, grated red onion, minced garlic, chopped parsley, chopped cilantro, ground cumin, ground coriander, salt, and black pepper. Do not overmix.
Divide the lamb mixture into 8 equal portions. Roll each portion into a log shape or large meatball, and optionally thread onto pre-soaked wooden skewers.
Place the formed koftas on a baking sheet, cover, and refrigerate for at least 30 minutes to help them hold their shape.
While the koftas chill, whisk together the Greek yogurt, lemon juice, and a pinch of salt in a small bowl to make the yogurt sauce. Keep chilled until ready to serve.
Preheat a grill or a large grill pan over medium-high heat. Lightly brush the koftas with olive oil.
Grill the koftas for 6 to 8 minutes, turning occasionally, until they are browned on all sides and cooked to an internal temperature of 160°F.
Remove the koftas from the grill and let them rest for 3 minutes.
Serve the grilled lamb koftas warm, accompanied by the chilled yogurt sauce, kalamata olives, and extra lemon wedges.