Finely chop the onion, garlic, parsley, and mint, or pulse in a food processor.
In a large bowl, mix the lamb, chopped aromatics, breadcrumbs, egg, and spices. Combine with your hands until well mixed.
Form the mixture into small patties, flattening slightly. You should get around 12–14.
Heat oil or tallow in a skillet over medium heat. Fry the koftas in batches, 3–4 minutes per side, until browned and cooked through.
Meanwhile, combine all sauce ingredients in a bowl and whisk until smooth.
Serve koftas warm with the yogurt tahini sauce.