Wash the thyme, shake dry. Strip leaves from the stalks and chop. Cut tomatoes into very thin strips. Cut feta into small cubes.
Soak the rolls in cold water for about 10 minutes. In the meantime peel and finely dice the onion. Squeeze the bread roll well and knead with onion, minced meat, egg, thyme, tomatoes and feta. Season with approx. 1 level tsp salt and approx. 1⁄2 tsp pepper.
Form 8 meatballs from the minced meat mass with wet hands. Heat the oil in a large pan. Fry the meatballs in it (possibly in portions) at medium heat for 8-10 minutes on each side.
Shape them into meatballs and fry them.