Mix yogurt and mint in small bowl. Cover. Refrigerate until ready to serve.
Heat oil in large skillet on medium heat. Add onion, 2 tablespoons of the barberries, garlic powder, allspice, cumin, paprika, sea salt and pepper; cook and stir until onions and barberries are tender, about 5 minutes. Set aside to cool.
Mix lamb, egg, panko and cooled onion mixture in large bowl. Shape into 20 (1 1/2-inch) meatballs.
Brown meatballs, in batches if necessary, in same large skillet on medium heat. Remove meatballs from skillet. Add shallots; cook and stir on medium heat until golden brown. Stir in remaining ingredients and another 1 tablespoon of the barberries. Bring to boil. Return meatballs to skillet. Reduce heat and simmer until meatballs are cooked through and sauce is slightly thickened, about 10 minutes.
Serve meatballs and sauce topped with the mint yogurt and remaining 1 tablespoon barberries.