Pound the beef slices thinly, then season with salt and pepper. Dust them with flour on both sides.
In a large pan or pot, heat the oil and sear the meat on both sides until golden brown. Remove the seared meat and set it aside.
In the same pan, add the onion and sauté until soft. Add the sliced mushrooms and sauté until golden and the water has evaporated.
Return the seared meat to the pan with the mushrooms. Pour in the red wine and let it reduce. Add the beef broth. Add the bay leaf and allspice.
Bring to a boil, then reduce the heat to a minimum and cover. Simmer over low heat for about 60-90 minutes, or until the meat is perfectly tender. If the sauce is too thin, you can thicken it with a little flour mixed with water.
Before serving, remove the bay leaf and allspice berries. Season with salt and pepper to taste.
Serve hot with traditional side dishes like potato dumplings (kluski śląskie), boiled potatoes, buckwheat (kasza), or mashed potatoes. Garnish with fresh chopped parsley.