Combine the ground meat, finely chopped tail fat, ground red pepper, red pepper flakes, crushed garlic, salt, and black pepper in a large bowl. Knead by hand for 10 minutes until the mixture reaches a paste-like consistency and the fat is fully combined with the meat.

Cover the kneaded mixture with plastic wrap and let it rest in the refrigerator for 30 minutes. Chilled mixture sticks to the skewers more easily and holds together better while cooking.

With wet hands, press portions of the mixture onto flat, wide skewers, shaping them into a thin, long, even layer. Keep the thickness even throughout so it cooks evenly.

Cook the kebabs over glowing charcoal, turning occasionally. Caution: Both sides must brown and the meat must be fully cooked, reaching an internal temperature of 71°C (160°F); the inside of the mixture should not remain pink. It takes about 12-15 minutes to cook.

Char the long green peppers over the same fire, and rub the onion with sumac. Place the kebab on hot lavash bread and serve with the charred peppers and sumac-rubbed onion.