In a large bowl, combine minced meat, chopped onion, chopped garlic, egg, mustard, spices for minced meat, oregano, and breadcrumbs. Mix well until combined.
Drain the olives, quarter them, and gently fold them into the meat mixture.
Shape the meat mixture into meatballs.
Heat clarified butter or oil in a large pan over medium-high heat. Once hot, add the meatballs and fry for 15 minutes, turning occasionally, until golden brown on all sides and the internal temperature reaches 71°C / 160°F.