In a large bowl, combine the ground beef, breadcrumbs, grated onion, minced garlic, parsley, mint, oregano, cumin, salt, black pepper, and beaten egg. Mix well until all ingredients are evenly incorporated.
Shape the mixture into small meatballs, about 1-2 inches in diameter.
Heat the olive oil in a large skillet over medium heat. Add the meatballs in batches and cook until browned on all sides and cooked through, about 10-12 minutes.
Remove the meatballs from the skillet and place on a paper towel-lined plate to drain excess oil.
Serve the meatballs hot with tzatziki sauce and pita bread, or as desired.
