Peel and finely dice the onion and garlic. Knead minced meat, onion, garlic, egg and breadcrumbs well. Season the minced mass with salt, pepper and thyme. Form small meatballs from the mixture and fry them in hot oil all around for about 10 minutes.
Clean, wash and chop the spring onions. Remove meatballs from the pan. Fry the spring onions in the frying fat for 3 minutes. Add the tomatoes, meatballs and olives. Season to taste with salt and pepper and simmer for 15 minutes.
Sprinkle with crumbled feta cheese just before serving.