Peel onion and garlic. Chop the onion finely, chop the garlic. Wash oregano, shake dry, pluck off leaves and chop coarsely. Heat the oil in a pot and fry the onion and garlic. Stir in tomato paste and sauté briefly. Add tomatoes and chop coarsely with a spatula. Pour in broth, add oregano, except for a little to sprinkle, and season with salt and pepper. Bring to the boil and simmer for about 10 minutes.
Drain cheese and cut into 16 slices. Dab schnitzel dry and cut in half crosswise. Cut open freezer bag, place cutlets between the bags and beat flat. Place cutlets on a large kitchen board, season with a little salt and pepper and brush each cutlet with 1 heaped tsp. pesto. Sprinkle with Italian herb mixture and cover each cutlet with 1 slice of mozzarella. Fold the cutlets over the mozzarella from two sides.
Whisk eggs, some salt and pepper on a deep plate. Put flour and panko separately on two more deep plates. Turn the schnitzel packs first in flour, then in egg and finally in Panko. Heat clarified butter in a large frying pan and fry the schnitzel parcels briefly in it until crispy. Drain on kitchen paper.
Season the tomato sauce with salt and pepper and place in an ovenproof dish. Place the schnitzel parcels in the sauce and cover with the remaining mozzarella slices. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for 25-30 minutes.
Wash the beans, drain, clean and break them. Cook the beans in boiling salted water for about 15 minutes. Wash parsley, shake dry, pluck off leaves and chop. Drain beans, add butter and parsley and toss well. Remove the schnitzel packet from the oven and sprinkle with remaining oregano.