Cut a pocket into each steak, season the meat inside and outside. For the filling mix cheese, onion cubes and herbs. Whisk the eggs, season with salt and pepper. Melt the butter in a pan and fry the scrambled eggs in it.
Let it cool down a little, then fold in the cheese-herb mixture. Fill the steaks with it and pin them with a toothpick.
Prepare three deep plates. In the first one fill the flour, in the second one whisk the eggs and in the third one mix the grated extra hard cheese and breadcrumbs. First turn the steaks in the flour, tap lightly, then pull through the eggs and finally turn in the breadcrumbs.
Heat the oil in a pan and fry the steaks in it on both sides for about 8 minutes until golden brown.