Cut the meat into pieces and beat it well on both sides. Cut the onion into half rings.
In a bowl, mix the meat with the onion, salt and pepper, add the ketchup and mix thoroughly. Put it in the refrigerator overnight (or longer).
Put the pieces of meat on a parchment-covered baking sheet, and spread the onions from the marinade on top of them. Bake in a preheated 200 degree oven for 30 minutes. You can cover the top with foil. While the meat is cooking, cut the garlic into thin slices and grate the cheese. Get the meat, distribute the chopped garlic and sprinkle with cheese, send it in the oven for another 10 minutes.
Serve the finished meat with herbs and vegetables.