Preheat oven to 400°F.

Combine grated onion, ground lamb, breadcrumbs, garlic, cilantro, cumin, coriander, paprika, cinnamon, cayenne, salt, and pepper in a bowl. Mix thoroughly until spices are evenly distributed.

Roll the mixture into 16 large meatballs and arrange on a sheet pan.

Toss sliced bell peppers and red onion wedges with olive oil, salt, and pepper, then scatter around the meatballs on the pan.

Spray meatballs with olive oil. Bake for 15 minutes until meatballs are nearly cooked through and vegetables are softened.

Switch oven to broil on high and cook for 5 more minutes to char the edges of the meatballs and peppers.

Sprinkle with fresh cilantro. Serve with warm flatbreads, tahini sauce, shredded lettuce, and sliced tomatoes.